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linux-next/block/cfq-iosched.c
Tahsin Erdogan 72ef799b3f block: do not merge requests without consulting with io scheduler 
Before merging a bio into an existing request, io scheduler is called to
get its approval first. However, the requests that come from a plug
flush may get merged by block layer without consulting with io
scheduler.

In case of CFQ, this can cause fairness problems. For instance, if a
request gets merged into a low weight cgroup's request, high weight cgroup
now will depend on low weight cgroup to get scheduled. If high weigt cgroup
needs that io request to complete before submitting more requests, then it
will also lose its timeslice.

Following script demonstrates the problem. Group g1 has a low weight, g2
and g3 have equal high weights but g2's requests are adjacent to g1's
requests so they are subject to merging. Due to these merges, g2 gets
poor disk time allocation.

cat > cfq-merge-repro.sh << "EOF"
#!/bin/bash
set -e

IO_ROOT=/mnt-cgroup/io

mkdir -p $IO_ROOT

if ! mount | grep -qw $IO_ROOT; then
  mount -t cgroup none -oblkio $IO_ROOT
fi

cd $IO_ROOT

for i in g1 g2 g3; do
  if [ -d $i ]; then
    rmdir $i
  fi
done

mkdir g1 && echo 10 > g1/blkio.weight
mkdir g2 && echo 495 > g2/blkio.weight
mkdir g3 && echo 495 > g3/blkio.weight

RUNTIME=10

(echo $BASHPID > g1/cgroup.procs &&
 fio --readonly --name name1 --filename /dev/sdb \
     --rw read --size 64k --bs 64k --time_based \
     --runtime=$RUNTIME --offset=0k &> /dev/null)&

(echo $BASHPID > g2/cgroup.procs &&
 fio --readonly --name name1 --filename /dev/sdb \
     --rw read --size 64k --bs 64k --time_based \
     --runtime=$RUNTIME --offset=64k &> /dev/null)&

(echo $BASHPID > g3/cgroup.procs &&
 fio --readonly --name name1 --filename /dev/sdb \
     --rw read --size 64k --bs 64k --time_based \
     --runtime=$RUNTIME --offset=256k &> /dev/null)&

sleep $((RUNTIME+1))

for i in g1 g2 g3; do
  echo ---- $i ----
  cat $i/blkio.time
done

EOF
# ./cfq-merge-repro.sh
---- g1 ----
8:16 162
---- g2 ----
8:16 165
---- g3 ----
8:16 686

After applying the patch:

# ./cfq-merge-repro.sh
---- g1 ----
8:16 90
---- g2 ----
8:16 445
---- g3 ----
8:16 471

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2016-07-20 21:35:12 -06:00

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/*
* CFQ, or complete fairness queueing, disk scheduler.
*
* Based on ideas from a previously unfinished io
* scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
*
* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/ktime.h>
#include <linux/rbtree.h>
#include <linux/ioprio.h>
#include <linux/blktrace_api.h>
#include <linux/blk-cgroup.h>
#include "blk.h"
/*
* tunables
*/
/* max queue in one round of service */
static const int cfq_quantum = 8;
static const u64 cfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
/* maximum backwards seek, in KiB */
static const int cfq_back_max = 16 * 1024;
/* penalty of a backwards seek */
static const int cfq_back_penalty = 2;
static const u64 cfq_slice_sync = NSEC_PER_SEC / 10;
static u64 cfq_slice_async = NSEC_PER_SEC / 25;
static const int cfq_slice_async_rq = 2;
static u64 cfq_slice_idle = NSEC_PER_SEC / 125;
static u64 cfq_group_idle = NSEC_PER_SEC / 125;
static const u64 cfq_target_latency = (u64)NSEC_PER_SEC * 3/10; /* 300 ms */
static const int cfq_hist_divisor = 4;
/*
* offset from end of service tree
*/
#define CFQ_IDLE_DELAY (NSEC_PER_SEC / 5)
/*
* below this threshold, we consider thinktime immediate
*/
#define CFQ_MIN_TT (2 * NSEC_PER_SEC / HZ)
#define CFQ_SLICE_SCALE (5)
#define CFQ_HW_QUEUE_MIN (5)
#define CFQ_SERVICE_SHIFT 12
#define CFQQ_SEEK_THR (sector_t)(8 * 100)
#define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0])
#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1])
static struct kmem_cache *cfq_pool;
#define CFQ_PRIO_LISTS IOPRIO_BE_NR
#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
#define sample_valid(samples) ((samples) > 80)
#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
/* blkio-related constants */
#define CFQ_WEIGHT_LEGACY_MIN 10
#define CFQ_WEIGHT_LEGACY_DFL 500
#define CFQ_WEIGHT_LEGACY_MAX 1000
struct cfq_ttime {
u64 last_end_request;
u64 ttime_total;
u64 ttime_mean;
unsigned long ttime_samples;
};
/*
* Most of our rbtree usage is for sorting with min extraction, so
* if we cache the leftmost node we don't have to walk down the tree
* to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
* move this into the elevator for the rq sorting as well.
*/
struct cfq_rb_root {
struct rb_root rb;
struct rb_node *left;
unsigned count;
u64 min_vdisktime;
struct cfq_ttime ttime;
};
#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
.ttime = {.last_end_request = ktime_get_ns(),},}
/*
* Per process-grouping structure
*/
struct cfq_queue {
/* reference count */
int ref;
/* various state flags, see below */
unsigned int flags;
/* parent cfq_data */
struct cfq_data *cfqd;
/* service_tree member */
struct rb_node rb_node;
/* service_tree key */
u64 rb_key;
/* prio tree member */
struct rb_node p_node;
/* prio tree root we belong to, if any */
struct rb_root *p_root;
/* sorted list of pending requests */
struct rb_root sort_list;
/* if fifo isn't expired, next request to serve */
struct request *next_rq;
/* requests queued in sort_list */
int queued[2];
/* currently allocated requests */
int allocated[2];
/* fifo list of requests in sort_list */
struct list_head fifo;
/* time when queue got scheduled in to dispatch first request. */
u64 dispatch_start;
u64 allocated_slice;
u64 slice_dispatch;
/* time when first request from queue completed and slice started. */
u64 slice_start;
u64 slice_end;
s64 slice_resid;
/* pending priority requests */
int prio_pending;
/* number of requests that are on the dispatch list or inside driver */
int dispatched;
/* io prio of this group */
unsigned short ioprio, org_ioprio;
unsigned short ioprio_class, org_ioprio_class;
pid_t pid;
u32 seek_history;
sector_t last_request_pos;
struct cfq_rb_root *service_tree;
struct cfq_queue *new_cfqq;
struct cfq_group *cfqg;
/* Number of sectors dispatched from queue in single dispatch round */
unsigned long nr_sectors;
};
/*
* First index in the service_trees.
* IDLE is handled separately, so it has negative index
*/
enum wl_class_t {
BE_WORKLOAD = 0,
RT_WORKLOAD = 1,
IDLE_WORKLOAD = 2,
CFQ_PRIO_NR,
};
/*
* Second index in the service_trees.
*/
enum wl_type_t {
ASYNC_WORKLOAD = 0,
SYNC_NOIDLE_WORKLOAD = 1,
SYNC_WORKLOAD = 2
};
struct cfqg_stats {
#ifdef CONFIG_CFQ_GROUP_IOSCHED
/* number of ios merged */
struct blkg_rwstat merged;
/* total time spent on device in ns, may not be accurate w/ queueing */
struct blkg_rwstat service_time;
/* total time spent waiting in scheduler queue in ns */
struct blkg_rwstat wait_time;
/* number of IOs queued up */
struct blkg_rwstat queued;
/* total disk time and nr sectors dispatched by this group */
struct blkg_stat time;
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* time not charged to this cgroup */
struct blkg_stat unaccounted_time;
/* sum of number of ios queued across all samples */
struct blkg_stat avg_queue_size_sum;
/* count of samples taken for average */
struct blkg_stat avg_queue_size_samples;
/* how many times this group has been removed from service tree */
struct blkg_stat dequeue;
/* total time spent waiting for it to be assigned a timeslice. */
struct blkg_stat group_wait_time;
/* time spent idling for this blkcg_gq */
struct blkg_stat idle_time;
/* total time with empty current active q with other requests queued */
struct blkg_stat empty_time;
/* fields after this shouldn't be cleared on stat reset */
uint64_t start_group_wait_time;
uint64_t start_idle_time;
uint64_t start_empty_time;
uint16_t flags;
#endif /* CONFIG_DEBUG_BLK_CGROUP */
#endif /* CONFIG_CFQ_GROUP_IOSCHED */
};
/* Per-cgroup data */
struct cfq_group_data {
/* must be the first member */
struct blkcg_policy_data cpd;
unsigned int weight;
unsigned int leaf_weight;
};
/* This is per cgroup per device grouping structure */
struct cfq_group {
/* must be the first member */
struct blkg_policy_data pd;
/* group service_tree member */
struct rb_node rb_node;
/* group service_tree key */
u64 vdisktime;
/*
* The number of active cfqgs and sum of their weights under this
* cfqg. This covers this cfqg's leaf_weight and all children's
* weights, but does not cover weights of further descendants.
*
* If a cfqg is on the service tree, it's active. An active cfqg
* also activates its parent and contributes to the children_weight
* of the parent.
*/
int nr_active;
unsigned int children_weight;
/*
* vfraction is the fraction of vdisktime that the tasks in this
* cfqg are entitled to. This is determined by compounding the
* ratios walking up from this cfqg to the root.
*
* It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
* vfractions on a service tree is approximately 1. The sum may
* deviate a bit due to rounding errors and fluctuations caused by
* cfqgs entering and leaving the service tree.
*/
unsigned int vfraction;
/*
* There are two weights - (internal) weight is the weight of this
* cfqg against the sibling cfqgs. leaf_weight is the wight of
* this cfqg against the child cfqgs. For the root cfqg, both
* weights are kept in sync for backward compatibility.
*/
unsigned int weight;
unsigned int new_weight;
unsigned int dev_weight;
unsigned int leaf_weight;
unsigned int new_leaf_weight;
unsigned int dev_leaf_weight;
/* number of cfqq currently on this group */
int nr_cfqq;
/*
* Per group busy queues average. Useful for workload slice calc. We
* create the array for each prio class but at run time it is used
* only for RT and BE class and slot for IDLE class remains unused.
* This is primarily done to avoid confusion and a gcc warning.
*/
unsigned int busy_queues_avg[CFQ_PRIO_NR];
/*
* rr lists of queues with requests. We maintain service trees for
* RT and BE classes. These trees are subdivided in subclasses
* of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
* class there is no subclassification and all the cfq queues go on
* a single tree service_tree_idle.
* Counts are embedded in the cfq_rb_root
*/
struct cfq_rb_root service_trees[2][3];
struct cfq_rb_root service_tree_idle;
u64 saved_wl_slice;
enum wl_type_t saved_wl_type;
enum wl_class_t saved_wl_class;
/* number of requests that are on the dispatch list or inside driver */
int dispatched;
struct cfq_ttime ttime;
struct cfqg_stats stats; /* stats for this cfqg */
/* async queue for each priority case */
struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
struct cfq_queue *async_idle_cfqq;
};
struct cfq_io_cq {
struct io_cq icq; /* must be the first member */
struct cfq_queue *cfqq[2];
struct cfq_ttime ttime;
int ioprio; /* the current ioprio */
#ifdef CONFIG_CFQ_GROUP_IOSCHED
uint64_t blkcg_serial_nr; /* the current blkcg serial */
#endif
};
/*
* Per block device queue structure
*/
struct cfq_data {
struct request_queue *queue;
/* Root service tree for cfq_groups */
struct cfq_rb_root grp_service_tree;
struct cfq_group *root_group;
/*
* The priority currently being served
*/
enum wl_class_t serving_wl_class;
enum wl_type_t serving_wl_type;
u64 workload_expires;
struct cfq_group *serving_group;
/*
* Each priority tree is sorted by next_request position. These
* trees are used when determining if two or more queues are
* interleaving requests (see cfq_close_cooperator).
*/
struct rb_root prio_trees[CFQ_PRIO_LISTS];
unsigned int busy_queues;
unsigned int busy_sync_queues;
int rq_in_driver;
int rq_in_flight[2];
/*
* queue-depth detection
*/
int rq_queued;
int hw_tag;
/*
* hw_tag can be
* -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
* 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
* 0 => no NCQ
*/
int hw_tag_est_depth;
unsigned int hw_tag_samples;
/*
* idle window management
*/
struct hrtimer idle_slice_timer;
struct work_struct unplug_work;
struct cfq_queue *active_queue;
struct cfq_io_cq *active_cic;
sector_t last_position;
/*
* tunables, see top of file
*/
unsigned int cfq_quantum;
unsigned int cfq_back_penalty;
unsigned int cfq_back_max;
unsigned int cfq_slice_async_rq;
unsigned int cfq_latency;
u64 cfq_fifo_expire[2];
u64 cfq_slice[2];
u64 cfq_slice_idle;
u64 cfq_group_idle;
u64 cfq_target_latency;
/*
* Fallback dummy cfqq for extreme OOM conditions
*/
struct cfq_queue oom_cfqq;
u64 last_delayed_sync;
};
static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
static void cfq_put_queue(struct cfq_queue *cfqq);
static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
enum wl_class_t class,
enum wl_type_t type)
{
if (!cfqg)
return NULL;
if (class == IDLE_WORKLOAD)
return &cfqg->service_tree_idle;
return &cfqg->service_trees[class][type];
}
enum cfqq_state_flags {
CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
CFQ_CFQQ_FLAG_sync, /* synchronous queue */
CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
};
#define CFQ_CFQQ_FNS(name) \
static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
{ \
(cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
} \
static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
{ \
(cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
} \
static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
{ \
return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
}
CFQ_CFQQ_FNS(on_rr);
CFQ_CFQQ_FNS(wait_request);
CFQ_CFQQ_FNS(must_dispatch);
CFQ_CFQQ_FNS(must_alloc_slice);
CFQ_CFQQ_FNS(fifo_expire);
CFQ_CFQQ_FNS(idle_window);
CFQ_CFQQ_FNS(prio_changed);
CFQ_CFQQ_FNS(slice_new);
CFQ_CFQQ_FNS(sync);
CFQ_CFQQ_FNS(coop);
CFQ_CFQQ_FNS(split_coop);
CFQ_CFQQ_FNS(deep);
CFQ_CFQQ_FNS(wait_busy);
#undef CFQ_CFQQ_FNS
#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
/* cfqg stats flags */
enum cfqg_stats_flags {
CFQG_stats_waiting = 0,
CFQG_stats_idling,
CFQG_stats_empty,
};
#define CFQG_FLAG_FNS(name) \
static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats) \
{ \
stats->flags |= (1 << CFQG_stats_##name); \
} \
static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats) \
{ \
stats->flags &= ~(1 << CFQG_stats_##name); \
} \
static inline int cfqg_stats_##name(struct cfqg_stats *stats) \
{ \
return (stats->flags & (1 << CFQG_stats_##name)) != 0; \
} \
CFQG_FLAG_FNS(waiting)
CFQG_FLAG_FNS(idling)
CFQG_FLAG_FNS(empty)
#undef CFQG_FLAG_FNS
/* This should be called with the queue_lock held. */
static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
{
unsigned long long now;
if (!cfqg_stats_waiting(stats))
return;
now = sched_clock();
if (time_after64(now, stats->start_group_wait_time))
blkg_stat_add(&stats->group_wait_time,
now - stats->start_group_wait_time);
cfqg_stats_clear_waiting(stats);
}
/* This should be called with the queue_lock held. */
static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
struct cfq_group *curr_cfqg)
{
struct cfqg_stats *stats = &cfqg->stats;
if (cfqg_stats_waiting(stats))
return;
if (cfqg == curr_cfqg)
return;
stats->start_group_wait_time = sched_clock();
cfqg_stats_mark_waiting(stats);
}
/* This should be called with the queue_lock held. */
static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
{
unsigned long long now;
if (!cfqg_stats_empty(stats))
return;
now = sched_clock();
if (time_after64(now, stats->start_empty_time))
blkg_stat_add(&stats->empty_time,
now - stats->start_empty_time);
cfqg_stats_clear_empty(stats);
}
static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
{
blkg_stat_add(&cfqg->stats.dequeue, 1);
}
static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
{
struct cfqg_stats *stats = &cfqg->stats;
if (blkg_rwstat_total(&stats->queued))
return;
/*
* group is already marked empty. This can happen if cfqq got new
* request in parent group and moved to this group while being added
* to service tree. Just ignore the event and move on.
*/
if (cfqg_stats_empty(stats))
return;
stats->start_empty_time = sched_clock();
cfqg_stats_mark_empty(stats);
}
static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
{
struct cfqg_stats *stats = &cfqg->stats;
if (cfqg_stats_idling(stats)) {
unsigned long long now = sched_clock();
if (time_after64(now, stats->start_idle_time))
blkg_stat_add(&stats->idle_time,
now - stats->start_idle_time);
cfqg_stats_clear_idling(stats);
}
}
static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
{
struct cfqg_stats *stats = &cfqg->stats;
BUG_ON(cfqg_stats_idling(stats));
stats->start_idle_time = sched_clock();
cfqg_stats_mark_idling(stats);
}
static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
{
struct cfqg_stats *stats = &cfqg->stats;
blkg_stat_add(&stats->avg_queue_size_sum,
blkg_rwstat_total(&stats->queued));
blkg_stat_add(&stats->avg_queue_size_samples, 1);
cfqg_stats_update_group_wait_time(stats);
}
#else /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
#endif /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
{
return pd ? container_of(pd, struct cfq_group, pd) : NULL;
}
static struct cfq_group_data
*cpd_to_cfqgd(struct blkcg_policy_data *cpd)
{
return cpd ? container_of(cpd, struct cfq_group_data, cpd) : NULL;
}
static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
{
return pd_to_blkg(&cfqg->pd);
}
static struct blkcg_policy blkcg_policy_cfq;
static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
{
return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
}
static struct cfq_group_data *blkcg_to_cfqgd(struct blkcg *blkcg)
{
return cpd_to_cfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_cfq));
}
static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
{
struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
return pblkg ? blkg_to_cfqg(pblkg) : NULL;
}
static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
struct cfq_group *ancestor)
{
return cgroup_is_descendant(cfqg_to_blkg(cfqg)->blkcg->css.cgroup,
cfqg_to_blkg(ancestor)->blkcg->css.cgroup);
}
static inline void cfqg_get(struct cfq_group *cfqg)
{
return blkg_get(cfqg_to_blkg(cfqg));
}
static inline void cfqg_put(struct cfq_group *cfqg)
{
return blkg_put(cfqg_to_blkg(cfqg));
}
#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) do { \
char __pbuf[128]; \
\
blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf)); \
blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \
cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
__pbuf, ##args); \
} while (0)
#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do { \
char __pbuf[128]; \
\
blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf)); \
blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args); \
} while (0)
static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
struct cfq_group *curr_cfqg, int op,
int op_flags)
{
blkg_rwstat_add(&cfqg->stats.queued, op, op_flags, 1);
cfqg_stats_end_empty_time(&cfqg->stats);
cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
}
static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
uint64_t time, unsigned long unaccounted_time)
{
blkg_stat_add(&cfqg->stats.time, time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
#endif
}
static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int op,
int op_flags)
{
blkg_rwstat_add(&cfqg->stats.queued, op, op_flags, -1);
}
static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int op,
int op_flags)
{
blkg_rwstat_add(&cfqg->stats.merged, op, op_flags, 1);
}
static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
uint64_t start_time, uint64_t io_start_time, int op,
int op_flags)
{
struct cfqg_stats *stats = &cfqg->stats;
unsigned long long now = sched_clock();
if (time_after64(now, io_start_time))
blkg_rwstat_add(&stats->service_time, op, op_flags,
now - io_start_time);
if (time_after64(io_start_time, start_time))
blkg_rwstat_add(&stats->wait_time, op, op_flags,
io_start_time - start_time);
}
/* @stats = 0 */
static void cfqg_stats_reset(struct cfqg_stats *stats)
{
/* queued stats shouldn't be cleared */
blkg_rwstat_reset(&stats->merged);
blkg_rwstat_reset(&stats->service_time);
blkg_rwstat_reset(&stats->wait_time);
blkg_stat_reset(&stats->time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
blkg_stat_reset(&stats->unaccounted_time);
blkg_stat_reset(&stats->avg_queue_size_sum);
blkg_stat_reset(&stats->avg_queue_size_samples);
blkg_stat_reset(&stats->dequeue);
blkg_stat_reset(&stats->group_wait_time);
blkg_stat_reset(&stats->idle_time);
blkg_stat_reset(&stats->empty_time);
#endif
}
/* @to += @from */
static void cfqg_stats_add_aux(struct cfqg_stats *to, struct cfqg_stats *from)
{
/* queued stats shouldn't be cleared */
blkg_rwstat_add_aux(&to->merged, &from->merged);
blkg_rwstat_add_aux(&to->service_time, &from->service_time);
blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
blkg_stat_add_aux(&from->time, &from->time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
blkg_stat_add_aux(&to->unaccounted_time, &from->unaccounted_time);
blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
blkg_stat_add_aux(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
blkg_stat_add_aux(&to->dequeue, &from->dequeue);
blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
blkg_stat_add_aux(&to->idle_time, &from->idle_time);
blkg_stat_add_aux(&to->empty_time, &from->empty_time);
#endif
}
/*
* Transfer @cfqg's stats to its parent's aux counts so that the ancestors'
* recursive stats can still account for the amount used by this cfqg after
* it's gone.
*/
static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
{
struct cfq_group *parent = cfqg_parent(cfqg);
lockdep_assert_held(cfqg_to_blkg(cfqg)->q->queue_lock);
if (unlikely(!parent))
return;
cfqg_stats_add_aux(&parent->stats, &cfqg->stats);
cfqg_stats_reset(&cfqg->stats);
}
#else /* CONFIG_CFQ_GROUP_IOSCHED */
static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
struct cfq_group *ancestor)
{
return true;
}
static inline void cfqg_get(struct cfq_group *cfqg) { }
static inline void cfqg_put(struct cfq_group *cfqg) { }
#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \
cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
##args)
#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
struct cfq_group *curr_cfqg, int op, int op_flags) { }
static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
uint64_t time, unsigned long unaccounted_time) { }
static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int op,
int op_flags) { }
static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int op,
int op_flags) { }
static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
uint64_t start_time, uint64_t io_start_time, int op,
int op_flags) { }
#endif /* CONFIG_CFQ_GROUP_IOSCHED */
#define cfq_log(cfqd, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
/* Traverses through cfq group service trees */
#define for_each_cfqg_st(cfqg, i, j, st) \
for (i = 0; i <= IDLE_WORKLOAD; i++) \
for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
: &cfqg->service_tree_idle; \
(i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
(i == IDLE_WORKLOAD && j == 0); \
j++, st = i < IDLE_WORKLOAD ? \
&cfqg->service_trees[i][j]: NULL) \
static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
struct cfq_ttime *ttime, bool group_idle)
{
u64 slice;
if (!sample_valid(ttime->ttime_samples))
return false;
if (group_idle)
slice = cfqd->cfq_group_idle;
else
slice = cfqd->cfq_slice_idle;
return ttime->ttime_mean > slice;
}
static inline bool iops_mode(struct cfq_data *cfqd)
{
/*
* If we are not idling on queues and it is a NCQ drive, parallel
* execution of requests is on and measuring time is not possible
* in most of the cases until and unless we drive shallower queue
* depths and that becomes a performance bottleneck. In such cases
* switch to start providing fairness in terms of number of IOs.
*/
if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
return true;
else
return false;
}
static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
{
if (cfq_class_idle(cfqq))
return IDLE_WORKLOAD;
if (cfq_class_rt(cfqq))
return RT_WORKLOAD;
return BE_WORKLOAD;
}
static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
{
if (!cfq_cfqq_sync(cfqq))
return ASYNC_WORKLOAD;
if (!cfq_cfqq_idle_window(cfqq))
return SYNC_NOIDLE_WORKLOAD;
return SYNC_WORKLOAD;
}
static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
struct cfq_data *cfqd,
struct cfq_group *cfqg)
{
if (wl_class == IDLE_WORKLOAD)
return cfqg->service_tree_idle.count;
return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
}
static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
struct cfq_group *cfqg)
{
return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
}
static void cfq_dispatch_insert(struct request_queue *, struct request *);
static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
struct cfq_io_cq *cic, struct bio *bio);
static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
{
/* cic->icq is the first member, %NULL will convert to %NULL */
return container_of(icq, struct cfq_io_cq, icq);
}
static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
struct io_context *ioc)
{
if (ioc)
return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
return NULL;
}
static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
{
return cic->cfqq[is_sync];
}
static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
bool is_sync)
{
cic->cfqq[is_sync] = cfqq;
}
static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
{
return cic->icq.q->elevator->elevator_data;
}
/*
* We regard a request as SYNC, if it's either a read or has the SYNC bit
* set (in which case it could also be direct WRITE).
*/
static inline bool cfq_bio_sync(struct bio *bio)
{
return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
}
/*
* scheduler run of queue, if there are requests pending and no one in the
* driver that will restart queueing
*/
static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
{
if (cfqd->busy_queues) {
cfq_log(cfqd, "schedule dispatch");
kblockd_schedule_work(&cfqd->unplug_work);
}
}
/*
* Scale schedule slice based on io priority. Use the sync time slice only
* if a queue is marked sync and has sync io queued. A sync queue with async
* io only, should not get full sync slice length.
*/
static inline u64 cfq_prio_slice(struct cfq_data *cfqd, bool sync,
unsigned short prio)
{
u64 base_slice = cfqd->cfq_slice[sync];
u64 slice = div_u64(base_slice, CFQ_SLICE_SCALE);
WARN_ON(prio >= IOPRIO_BE_NR);
return base_slice + (slice * (4 - prio));
}
static inline u64
cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
}
/**
* cfqg_scale_charge - scale disk time charge according to cfqg weight
* @charge: disk time being charged
* @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
*
* Scale @charge according to @vfraction, which is in range (0, 1]. The
* scaling is inversely proportional.
*
* scaled = charge / vfraction
*
* The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
*/
static inline u64 cfqg_scale_charge(u64 charge,
unsigned int vfraction)
{
u64 c = charge << CFQ_SERVICE_SHIFT; /* make it fixed point */
/* charge / vfraction */
c <<= CFQ_SERVICE_SHIFT;
return div_u64(c, vfraction);
}
static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
{
s64 delta = (s64)(vdisktime - min_vdisktime);
if (delta > 0)
min_vdisktime = vdisktime;
return min_vdisktime;
}
static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
{
s64 delta = (s64)(vdisktime - min_vdisktime);
if (delta < 0)
min_vdisktime = vdisktime;
return min_vdisktime;
}
static void update_min_vdisktime(struct cfq_rb_root *st)
{
struct cfq_group *cfqg;
if (st->left) {
cfqg = rb_entry_cfqg(st->left);
st->min_vdisktime = max_vdisktime(st->min_vdisktime,
cfqg->vdisktime);
}
}
/*
* get averaged number of queues of RT/BE priority.
* average is updated, with a formula that gives more weight to higher numbers,
* to quickly follows sudden increases and decrease slowly
*/
static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
struct cfq_group *cfqg, bool rt)
{
unsigned min_q, max_q;
unsigned mult = cfq_hist_divisor - 1;
unsigned round = cfq_hist_divisor / 2;
unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
min_q = min(cfqg->busy_queues_avg[rt], busy);
max_q = max(cfqg->busy_queues_avg[rt], busy);
cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
cfq_hist_divisor;
return cfqg->busy_queues_avg[rt];
}
static inline u64
cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT;
}
static inline u64
cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
u64 slice = cfq_prio_to_slice(cfqd, cfqq);
if (cfqd->cfq_latency) {
/*
* interested queues (we consider only the ones with the same
* priority class in the cfq group)
*/
unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
cfq_class_rt(cfqq));
u64 sync_slice = cfqd->cfq_slice[1];
u64 expect_latency = sync_slice * iq;
u64 group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
if (expect_latency > group_slice) {
u64 base_low_slice = 2 * cfqd->cfq_slice_idle;
u64 low_slice;
/* scale low_slice according to IO priority
* and sync vs async */
low_slice = div64_u64(base_low_slice*slice, sync_slice);
low_slice = min(slice, low_slice);
/* the adapted slice value is scaled to fit all iqs
* into the target latency */
slice = div64_u64(slice*group_slice, expect_latency);
slice = max(slice, low_slice);
}
}
return slice;
}
static inline void
cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
u64 slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
u64 now = ktime_get_ns();
cfqq->slice_start = now;
cfqq->slice_end = now + slice;
cfqq->allocated_slice = slice;
cfq_log_cfqq(cfqd, cfqq, "set_slice=%llu", cfqq->slice_end - now);
}
/*
* We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
* isn't valid until the first request from the dispatch is activated
* and the slice time set.
*/
static inline bool cfq_slice_used(struct cfq_queue *cfqq)
{
if (cfq_cfqq_slice_new(cfqq))
return false;
if (ktime_get_ns() < cfqq->slice_end)
return false;
return true;
}
/*
* Lifted from AS - choose which of rq1 and rq2 that is best served now.
* We choose the request that is closest to the head right now. Distance
* behind the head is penalized and only allowed to a certain extent.
*/
static struct request *
cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
{
sector_t s1, s2, d1 = 0, d2 = 0;
unsigned long back_max;
#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
unsigned wrap = 0; /* bit mask: requests behind the disk head? */
if (rq1 == NULL || rq1 == rq2)
return rq2;
if (rq2 == NULL)
return rq1;
if (rq_is_sync(rq1) != rq_is_sync(rq2))
return rq_is_sync(rq1) ? rq1 : rq2;
if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
s1 = blk_rq_pos(rq1);
s2 = blk_rq_pos(rq2);
/*
* by definition, 1KiB is 2 sectors
*/
back_max = cfqd->cfq_back_max * 2;
/*
* Strict one way elevator _except_ in the case where we allow
* short backward seeks which are biased as twice the cost of a
* similar forward seek.
*/
if (s1 >= last)
d1 = s1 - last;
else if (s1 + back_max >= last)
d1 = (last - s1) * cfqd->cfq_back_penalty;
else
wrap |= CFQ_RQ1_WRAP;
if (s2 >= last)
d2 = s2 - last;
else if (s2 + back_max >= last)
d2 = (last - s2) * cfqd->cfq_back_penalty;
else
wrap |= CFQ_RQ2_WRAP;
/* Found required data */
/*
* By doing switch() on the bit mask "wrap" we avoid having to
* check two variables for all permutations: --> faster!
*/
switch (wrap) {
case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
if (d1 < d2)
return rq1;
else if (d2 < d1)
return rq2;
else {
if (s1 >= s2)
return rq1;
else
return rq2;
}
case CFQ_RQ2_WRAP:
return rq1;
case CFQ_RQ1_WRAP:
return rq2;
case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
default:
/*
* Since both rqs are wrapped,
* start with the one that's further behind head
* (--> only *one* back seek required),
* since back seek takes more time than forward.
*/
if (s1 <= s2)
return rq1;
else
return rq2;
}
}
/*
* The below is leftmost cache rbtree addon
*/
static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
{
/* Service tree is empty */
if (!root->count)
return NULL;
if (!root->left)
root->left = rb_first(&root->rb);
if (root->left)
return rb_entry(root->left, struct cfq_queue, rb_node);
return NULL;
}
static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
{
if (!root->left)
root->left = rb_first(&root->rb);
if (root->left)
return rb_entry_cfqg(root->left);
return NULL;
}
static void rb_erase_init(struct rb_node *n, struct rb_root *root)
{
rb_erase(n, root);
RB_CLEAR_NODE(n);
}
static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
{
if (root->left == n)
root->left = NULL;
rb_erase_init(n, &root->rb);
--root->count;
}
/*
* would be nice to take fifo expire time into account as well
*/
static struct request *
cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct request *last)
{
struct rb_node *rbnext = rb_next(&last->rb_node);
struct rb_node *rbprev = rb_prev(&last->rb_node);
struct request *next = NULL, *prev = NULL;
BUG_ON(RB_EMPTY_NODE(&last->rb_node));
if (rbprev)
prev = rb_entry_rq(rbprev);
if (rbnext)
next = rb_entry_rq(rbnext);
else {
rbnext = rb_first(&cfqq->sort_list);
if (rbnext && rbnext != &last->rb_node)
next = rb_entry_rq(rbnext);
}
return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
}
static u64 cfq_slice_offset(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
/*
* just an approximation, should be ok.
*/
return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
}
static inline s64
cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
{
return cfqg->vdisktime - st->min_vdisktime;
}
static void
__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
{
struct rb_node **node = &st->rb.rb_node;
struct rb_node *parent = NULL;
struct cfq_group *__cfqg;
s64 key = cfqg_key(st, cfqg);
int left = 1;
while (*node != NULL) {
parent = *node;
__cfqg = rb_entry_cfqg(parent);
if (key < cfqg_key(st, __cfqg))
node = &parent->rb_left;
else {
node = &parent->rb_right;
left = 0;
}
}
if (left)
st->left = &cfqg->rb_node;
rb_link_node(&cfqg->rb_node, parent, node);
rb_insert_color(&cfqg->rb_node, &st->rb);
}
/*
* This has to be called only on activation of cfqg
*/
static void
cfq_update_group_weight(struct cfq_group *cfqg)
{
if (cfqg->new_weight) {
cfqg->weight = cfqg->new_weight;
cfqg->new_weight = 0;
}
}
static void
cfq_update_group_leaf_weight(struct cfq_group *cfqg)
{
BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
if (cfqg->new_leaf_weight) {
cfqg->leaf_weight = cfqg->new_leaf_weight;
cfqg->new_leaf_weight = 0;
}
}
static void
cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
{
unsigned int vfr = 1 << CFQ_SERVICE_SHIFT; /* start with 1 */
struct cfq_group *pos = cfqg;
struct cfq_group *parent;
bool propagate;
/* add to the service tree */
BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
/*
* Update leaf_weight. We cannot update weight at this point
* because cfqg might already have been activated and is
* contributing its current weight to the parent's child_weight.
*/
cfq_update_group_leaf_weight(cfqg);
__cfq_group_service_tree_add(st, cfqg);
/*
* Activate @cfqg and calculate the portion of vfraction @cfqg is
* entitled to. vfraction is calculated by walking the tree
* towards the root calculating the fraction it has at each level.
* The compounded ratio is how much vfraction @cfqg owns.
*
* Start with the proportion tasks in this cfqg has against active
* children cfqgs - its leaf_weight against children_weight.
*/
propagate = !pos->nr_active++;
pos->children_weight += pos->leaf_weight;
vfr = vfr * pos->leaf_weight / pos->children_weight;
/*
* Compound ->weight walking up the tree. Both activation and
* vfraction calculation are done in the same loop. Propagation
* stops once an already activated node is met. vfraction
* calculation should always continue to the root.
*/
while ((parent = cfqg_parent(pos))) {
if (propagate) {
cfq_update_group_weight(pos);
propagate = !parent->nr_active++;
parent->children_weight += pos->weight;
}
vfr = vfr * pos->weight / parent->children_weight;
pos = parent;
}
cfqg->vfraction = max_t(unsigned, vfr, 1);
}
static void
cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
struct cfq_group *__cfqg;
struct rb_node *n;
cfqg->nr_cfqq++;
if (!RB_EMPTY_NODE(&cfqg->rb_node))
return;
/*
* Currently put the group at the end. Later implement something
* so that groups get lesser vtime based on their weights, so that
* if group does not loose all if it was not continuously backlogged.
*/
n = rb_last(&st->rb);
if (n) {
__cfqg = rb_entry_cfqg(n);
cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
} else
cfqg->vdisktime = st->min_vdisktime;
cfq_group_service_tree_add(st, cfqg);
}
static void
cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
{
struct cfq_group *pos = cfqg;
bool propagate;
/*
* Undo activation from cfq_group_service_tree_add(). Deactivate
* @cfqg and propagate deactivation upwards.
*/
propagate = !--pos->nr_active;
pos->children_weight -= pos->leaf_weight;
while (propagate) {
struct cfq_group *parent = cfqg_parent(pos);
/* @pos has 0 nr_active at this point */
WARN_ON_ONCE(pos->children_weight);
pos->vfraction = 0;
if (!parent)
break;
propagate = !--parent->nr_active;
parent->children_weight -= pos->weight;
pos = parent;
}
/* remove from the service tree */
if (!RB_EMPTY_NODE(&cfqg->rb_node))
cfq_rb_erase(&cfqg->rb_node, st);
}
static void
cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
BUG_ON(cfqg->nr_cfqq < 1);
cfqg->nr_cfqq--;
/* If there are other cfq queues under this group, don't delete it */
if (cfqg->nr_cfqq)
return;
cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
cfq_group_service_tree_del(st, cfqg);
cfqg->saved_wl_slice = 0;
cfqg_stats_update_dequeue(cfqg);
}
static inline u64 cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
u64 *unaccounted_time)
{
u64 slice_used;
u64 now = ktime_get_ns();
/*
* Queue got expired before even a single request completed or
* got expired immediately after first request completion.
*/
if (!cfqq->slice_start || cfqq->slice_start == now) {
/*
* Also charge the seek time incurred to the group, otherwise
* if there are mutiple queues in the group, each can dispatch
* a single request on seeky media and cause lots of seek time
* and group will never know it.
*/
slice_used = max_t(u64, (now - cfqq->dispatch_start),
jiffies_to_nsecs(1));
} else {
slice_used = now - cfqq->slice_start;
if (slice_used > cfqq->allocated_slice) {
*unaccounted_time = slice_used - cfqq->allocated_slice;
slice_used = cfqq->allocated_slice;
}
if (cfqq->slice_start > cfqq->dispatch_start)
*unaccounted_time += cfqq->slice_start -
cfqq->dispatch_start;
}
return slice_used;
}
static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
struct cfq_queue *cfqq)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
u64 used_sl, charge, unaccounted_sl = 0;
int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
- cfqg->service_tree_idle.count;
unsigned int vfr;
u64 now = ktime_get_ns();
BUG_ON(nr_sync < 0);
used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
if (iops_mode(cfqd))
charge = cfqq->slice_dispatch;
else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
charge = cfqq->allocated_slice;
/*
* Can't update vdisktime while on service tree and cfqg->vfraction
* is valid only while on it. Cache vfr, leave the service tree,
* update vdisktime and go back on. The re-addition to the tree
* will also update the weights as necessary.
*/
vfr = cfqg->vfraction;
cfq_group_service_tree_del(st, cfqg);
cfqg->vdisktime += cfqg_scale_charge(charge, vfr);
cfq_group_service_tree_add(st, cfqg);
/* This group is being expired. Save the context */
if (cfqd->workload_expires > now) {
cfqg->saved_wl_slice = cfqd->workload_expires - now;
cfqg->saved_wl_type = cfqd->serving_wl_type;
cfqg->saved_wl_class = cfqd->serving_wl_class;
} else
cfqg->saved_wl_slice = 0;
cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
st->min_vdisktime);
cfq_log_cfqq(cfqq->cfqd, cfqq,
"sl_used=%llu disp=%llu charge=%llu iops=%u sect=%lu",
used_sl, cfqq->slice_dispatch, charge,
iops_mode(cfqd), cfqq->nr_sectors);
cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
cfqg_stats_set_start_empty_time(cfqg);
}
/**
* cfq_init_cfqg_base - initialize base part of a cfq_group
* @cfqg: cfq_group to initialize
*
* Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
* is enabled or not.
*/
static void cfq_init_cfqg_base(struct cfq_group *cfqg)
{
struct cfq_rb_root *st;
int i, j;
for_each_cfqg_st(cfqg, i, j, st)
*st = CFQ_RB_ROOT;
RB_CLEAR_NODE(&cfqg->rb_node);
cfqg->ttime.last_end_request = ktime_get_ns();
}
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
bool on_dfl, bool reset_dev, bool is_leaf_weight);
static void cfqg_stats_exit(struct cfqg_stats *stats)
{
blkg_rwstat_exit(&stats->merged);
blkg_rwstat_exit(&stats->service_time);
blkg_rwstat_exit(&stats->wait_time);
blkg_rwstat_exit(&stats->queued);
blkg_stat_exit(&stats->time);
#ifdef CONFIG_DEBUG_BLK_CGROUP
blkg_stat_exit(&stats->unaccounted_time);
blkg_stat_exit(&stats->avg_queue_size_sum);
blkg_stat_exit(&stats->avg_queue_size_samples);
blkg_stat_exit(&stats->dequeue);
blkg_stat_exit(&stats->group_wait_time);
blkg_stat_exit(&stats->idle_time);
blkg_stat_exit(&stats->empty_time);
#endif
}
static int cfqg_stats_init(struct cfqg_stats *stats, gfp_t gfp)
{
if (blkg_rwstat_init(&stats->merged, gfp) ||
blkg_rwstat_init(&stats->service_time, gfp) ||
blkg_rwstat_init(&stats->wait_time, gfp) ||
blkg_rwstat_init(&stats->queued, gfp) ||
blkg_stat_init(&stats->time, gfp))
goto err;
#ifdef CONFIG_DEBUG_BLK_CGROUP
if (blkg_stat_init(&stats->unaccounted_time, gfp) ||
blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
blkg_stat_init(&stats->dequeue, gfp) ||
blkg_stat_init(&stats->group_wait_time, gfp) ||
blkg_stat_init(&stats->idle_time, gfp) ||
blkg_stat_init(&stats->empty_time, gfp))
goto err;
#endif
return 0;
err:
cfqg_stats_exit(stats);
return -ENOMEM;
}
static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp)
{
struct cfq_group_data *cgd;
cgd = kzalloc(sizeof(*cgd), GFP_KERNEL);
if (!cgd)
return NULL;
return &cgd->cpd;
}
static void cfq_cpd_init(struct blkcg_policy_data *cpd)
{
struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
unsigned int weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
if (cpd_to_blkcg(cpd) == &blkcg_root)
weight *= 2;
cgd->weight = weight;
cgd->leaf_weight = weight;
}
static void cfq_cpd_free(struct blkcg_policy_data *cpd)
{
kfree(cpd_to_cfqgd(cpd));
}
static void cfq_cpd_bind(struct blkcg_policy_data *cpd)
{
struct blkcg *blkcg = cpd_to_blkcg(cpd);
bool on_dfl = cgroup_subsys_on_dfl(io_cgrp_subsys);
unsigned int weight = on_dfl ? CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
if (blkcg == &blkcg_root)
weight *= 2;
WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, false));
WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, true));
}
static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)
{
struct cfq_group *cfqg;
cfqg = kzalloc_node(sizeof(*cfqg), gfp, node);
if (!cfqg)
return NULL;
cfq_init_cfqg_base(cfqg);
if (cfqg_stats_init(&cfqg->stats, gfp)) {
kfree(cfqg);
return NULL;
}
return &cfqg->pd;
}
static void cfq_pd_init(struct blkg_policy_data *pd)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
struct cfq_group_data *cgd = blkcg_to_cfqgd(pd->blkg->blkcg);
cfqg->weight = cgd->weight;
cfqg->leaf_weight = cgd->leaf_weight;
}
static void cfq_pd_offline(struct blkg_policy_data *pd)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
int i;
for (i = 0; i < IOPRIO_BE_NR; i++) {
if (cfqg->async_cfqq[0][i])
cfq_put_queue(cfqg->async_cfqq[0][i]);
if (cfqg->async_cfqq[1][i])
cfq_put_queue(cfqg->async_cfqq[1][i]);
}
if (cfqg->async_idle_cfqq)
cfq_put_queue(cfqg->async_idle_cfqq);
/*
* @blkg is going offline and will be ignored by
* blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so
* that they don't get lost. If IOs complete after this point, the
* stats for them will be lost. Oh well...
*/
cfqg_stats_xfer_dead(cfqg);
}
static void cfq_pd_free(struct blkg_policy_data *pd)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
cfqg_stats_exit(&cfqg->stats);
return kfree(cfqg);
}
static void cfq_pd_reset_stats(struct blkg_policy_data *pd)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
cfqg_stats_reset(&cfqg->stats);
}
static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
struct blkcg *blkcg)
{
struct blkcg_gq *blkg;
blkg = blkg_lookup(blkcg, cfqd->queue);
if (likely(blkg))
return blkg_to_cfqg(blkg);
return NULL;
}
static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
{
cfqq->cfqg = cfqg;
/* cfqq reference on cfqg */
cfqg_get(cfqg);
}
static u64 cfqg_prfill_weight_device(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
if (!cfqg->dev_weight)
return 0;
return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
}
static int cfqg_print_weight_device(struct seq_file *sf, void *v)
{
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
cfqg_prfill_weight_device, &blkcg_policy_cfq,
0, false);
return 0;
}
static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
if (!cfqg->dev_leaf_weight)
return 0;
return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
}
static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v)
{
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq,
0, false);
return 0;
}
static int cfq_print_weight(struct seq_file *sf, void *v)
{
struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
unsigned int val = 0;
if (cgd)
val = cgd->weight;
seq_printf(sf, "%u\n", val);
return 0;
}
static int cfq_print_leaf_weight(struct seq_file *sf, void *v)
{
struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
unsigned int val = 0;
if (cgd)
val = cgd->leaf_weight;
seq_printf(sf, "%u\n", val);
return 0;
}
static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off,
bool on_dfl, bool is_leaf_weight)
{
unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
struct blkcg *blkcg = css_to_blkcg(of_css(of));
struct blkg_conf_ctx ctx;
struct cfq_group *cfqg;
struct cfq_group_data *cfqgd;
int ret;
u64 v;
ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
if (ret)
return ret;
if (sscanf(ctx.body, "%llu", &v) == 1) {
/* require "default" on dfl */
ret = -ERANGE;
if (!v && on_dfl)
goto out_finish;
} else if (!strcmp(strim(ctx.body), "default")) {
v = 0;
} else {
ret = -EINVAL;
goto out_finish;
}
cfqg = blkg_to_cfqg(ctx.blkg);
cfqgd = blkcg_to_cfqgd(blkcg);
ret = -ERANGE;
if (!v || (v >= min && v <= max)) {
if (!is_leaf_weight) {
cfqg->dev_weight = v;
cfqg->new_weight = v ?: cfqgd->weight;
} else {
cfqg->dev_leaf_weight = v;
cfqg->new_leaf_weight = v ?: cfqgd->leaf_weight;
}
ret = 0;
}
out_finish:
blkg_conf_finish(&ctx);
return ret ?: nbytes;
}
static ssize_t cfqg_set_weight_device(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
return __cfqg_set_weight_device(of, buf, nbytes, off, false, false);
}
static ssize_t cfqg_set_leaf_weight_device(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
return __cfqg_set_weight_device(of, buf, nbytes, off, false, true);
}
static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
bool on_dfl, bool reset_dev, bool is_leaf_weight)
{
unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
struct blkcg *blkcg = css_to_blkcg(css);
struct blkcg_gq *blkg;
struct cfq_group_data *cfqgd;
int ret = 0;
if (val < min || val > max)
return -ERANGE;
spin_lock_irq(&blkcg->lock);
cfqgd = blkcg_to_cfqgd(blkcg);
if (!cfqgd) {
ret = -EINVAL;
goto out;
}
if (!is_leaf_weight)
cfqgd->weight = val;
else
cfqgd->leaf_weight = val;
hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
struct cfq_group *cfqg = blkg_to_cfqg(blkg);
if (!cfqg)
continue;
if (!is_leaf_weight) {
if (reset_dev)
cfqg->dev_weight = 0;
if (!cfqg->dev_weight)
cfqg->new_weight = cfqgd->weight;
} else {
if (reset_dev)
cfqg->dev_leaf_weight = 0;
if (!cfqg->dev_leaf_weight)
cfqg->new_leaf_weight = cfqgd->leaf_weight;
}
}
out:
spin_unlock_irq(&blkcg->lock);
return ret;
}
static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
u64 val)
{
return __cfq_set_weight(css, val, false, false, false);
}
static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
return __cfq_set_weight(css, val, false, false, true);
}
static int cfqg_print_stat(struct seq_file *sf, void *v)
{
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
&blkcg_policy_cfq, seq_cft(sf)->private, false);
return 0;
}
static int cfqg_print_rwstat(struct seq_file *sf, void *v)
{
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
&blkcg_policy_cfq, seq_cft(sf)->private, true);
return 0;
}
static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
&blkcg_policy_cfq, off);
return __blkg_prfill_u64(sf, pd, sum);
}
static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
&blkcg_policy_cfq, off);
return __blkg_prfill_rwstat(sf, pd, &sum);
}
static int cfqg_print_stat_recursive(struct seq_file *sf, void *v)
{
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
cfqg_prfill_stat_recursive, &blkcg_policy_cfq,
seq_cft(sf)->private, false);
return 0;
}
static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
{
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq,
seq_cft(sf)->private, true);
return 0;
}
static u64 cfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
int off)
{
u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
return __blkg_prfill_u64(sf, pd, sum >> 9);
}
static int cfqg_print_stat_sectors(struct seq_file *sf, void *v)
{
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
cfqg_prfill_sectors, &blkcg_policy_cfq, 0, false);
return 0;
}
static u64 cfqg_prfill_sectors_recursive(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
offsetof(struct blkcg_gq, stat_bytes));
u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
return __blkg_prfill_u64(sf, pd, sum >> 9);
}
static int cfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
{
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
cfqg_prfill_sectors_recursive, &blkcg_policy_cfq, 0,
false);
return 0;
}
#ifdef CONFIG_DEBUG_BLK_CGROUP
static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
struct blkg_policy_data *pd, int off)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
u64 v = 0;
if (samples) {
v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
v = div64_u64(v, samples);
}
__blkg_prfill_u64(sf, pd, v);
return 0;
}
/* print avg_queue_size */
static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v)
{
blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
cfqg_prfill_avg_queue_size, &blkcg_policy_cfq,
0, false);
return 0;
}
#endif /* CONFIG_DEBUG_BLK_CGROUP */
static struct cftype cfq_blkcg_legacy_files[] = {
/* on root, weight is mapped to leaf_weight */
{
.name = "weight_device",
.flags = CFTYPE_ONLY_ON_ROOT,
.seq_show = cfqg_print_leaf_weight_device,
.write = cfqg_set_leaf_weight_device,
},
{
.name = "weight",
.flags = CFTYPE_ONLY_ON_ROOT,
.seq_show = cfq_print_leaf_weight,
.write_u64 = cfq_set_leaf_weight,
},
/* no such mapping necessary for !roots */
{
.name = "weight_device",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = cfqg_print_weight_device,
.write = cfqg_set_weight_device,
},
{
.name = "weight",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = cfq_print_weight,
.write_u64 = cfq_set_weight,
},
{
.name = "leaf_weight_device",
.seq_show = cfqg_print_leaf_weight_device,
.write = cfqg_set_leaf_weight_device,
},
{
.name = "leaf_weight",
.seq_show = cfq_print_leaf_weight,
.write_u64 = cfq_set_leaf_weight,
},
/* statistics, covers only the tasks in the cfqg */
{
.name = "time",
.private = offsetof(struct cfq_group, stats.time),
.seq_show = cfqg_print_stat,
},
{
.name = "sectors",
.seq_show = cfqg_print_stat_sectors,
},
{
.name = "io_service_bytes",
.private = (unsigned long)&blkcg_policy_cfq,
.seq_show = blkg_print_stat_bytes,
},
{
.name = "io_serviced",
.private = (unsigned long)&blkcg_policy_cfq,
.seq_show = blkg_print_stat_ios,
},
{
.name = "io_service_time",
.private = offsetof(struct cfq_group, stats.service_time),
.seq_show = cfqg_print_rwstat,
},
{
.name = "io_wait_time",
.private = offsetof(struct cfq_group, stats.wait_time),
.seq_show = cfqg_print_rwstat,
},
{
.name = "io_merged",
.private = offsetof(struct cfq_group, stats.merged),
.seq_show = cfqg_print_rwstat,
},
{
.name = "io_queued",
.private = offsetof(struct cfq_group, stats.queued),
.seq_show = cfqg_print_rwstat,
},
/* the same statictics which cover the cfqg and its descendants */
{
.name = "time_recursive",
.private = offsetof(struct cfq_group, stats.time),
.seq_show = cfqg_print_stat_recursive,
},
{
.name = "sectors_recursive",
.seq_show = cfqg_print_stat_sectors_recursive,
},
{
.name = "io_service_bytes_recursive",
.private = (unsigned long)&blkcg_policy_cfq,
.seq_show = blkg_print_stat_bytes_recursive,
},
{
.name = "io_serviced_recursive",
.private = (unsigned long)&blkcg_policy_cfq,
.seq_show = blkg_print_stat_ios_recursive,
},
{
.name = "io_service_time_recursive",
.private = offsetof(struct cfq_group, stats.service_time),
.seq_show = cfqg_print_rwstat_recursive,
},
{
.name = "io_wait_time_recursive",
.private = offsetof(struct cfq_group, stats.wait_time),
.seq_show = cfqg_print_rwstat_recursive,
},
{
.name = "io_merged_recursive",
.private = offsetof(struct cfq_group, stats.merged),
.seq_show = cfqg_print_rwstat_recursive,
},
{
.name = "io_queued_recursive",
.private = offsetof(struct cfq_group, stats.queued),
.seq_show = cfqg_print_rwstat_recursive,
},
#ifdef CONFIG_DEBUG_BLK_CGROUP
{
.name = "avg_queue_size",
.seq_show = cfqg_print_avg_queue_size,
},
{
.name = "group_wait_time",
.private = offsetof(struct cfq_group, stats.group_wait_time),
.seq_show = cfqg_print_stat,
},
{
.name = "idle_time",
.private = offsetof(struct cfq_group, stats.idle_time),
.seq_show = cfqg_print_stat,
},
{
.name = "empty_time",
.private = offsetof(struct cfq_group, stats.empty_time),
.seq_show = cfqg_print_stat,
},
{
.name = "dequeue",
.private = offsetof(struct cfq_group, stats.dequeue),
.seq_show = cfqg_print_stat,
},
{
.name = "unaccounted_time",
.private = offsetof(struct cfq_group, stats.unaccounted_time),
.seq_show = cfqg_print_stat,
},
#endif /* CONFIG_DEBUG_BLK_CGROUP */
{ } /* terminate */
};
static int cfq_print_weight_on_dfl(struct seq_file *sf, void *v)
{
struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
seq_printf(sf, "default %u\n", cgd->weight);
blkcg_print_blkgs(sf, blkcg, cfqg_prfill_weight_device,
&blkcg_policy_cfq, 0, false);
return 0;
}
static ssize_t cfq_set_weight_on_dfl(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
char *endp;
int ret;
u64 v;
buf = strim(buf);
/* "WEIGHT" or "default WEIGHT" sets the default weight */
v = simple_strtoull(buf, &endp, 0);
if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {
ret = __cfq_set_weight(of_css(of), v, true, false, false);
return ret ?: nbytes;
}
/* "MAJ:MIN WEIGHT" */
return __cfqg_set_weight_device(of, buf, nbytes, off, true, false);
}
static struct cftype cfq_blkcg_files[] = {
{
.name = "weight",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = cfq_print_weight_on_dfl,
.write = cfq_set_weight_on_dfl,
},
{ } /* terminate */
};
#else /* GROUP_IOSCHED */
static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
struct blkcg *blkcg)
{
return cfqd->root_group;
}
static inline void
cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
cfqq->cfqg = cfqg;
}
#endif /* GROUP_IOSCHED */
/*
* The cfqd->service_trees holds all pending cfq_queue's that have
* requests waiting to be processed. It is sorted in the order that
* we will service the queues.
*/
static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
bool add_front)
{
struct rb_node **p, *parent;
struct cfq_queue *__cfqq;
u64 rb_key;
struct cfq_rb_root *st;
int left;
int new_cfqq = 1;
u64 now = ktime_get_ns();
st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
if (cfq_class_idle(cfqq)) {
rb_key = CFQ_IDLE_DELAY;
parent = rb_last(&st->rb);
if (parent && parent != &cfqq->rb_node) {
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
rb_key += __cfqq->rb_key;
} else
rb_key += now;
} else if (!add_front) {
/*
* Get our rb key offset. Subtract any residual slice
* value carried from last service. A negative resid
* count indicates slice overrun, and this should position
* the next service time further away in the tree.
*/
rb_key = cfq_slice_offset(cfqd, cfqq) + now;
rb_key -= cfqq->slice_resid;
cfqq->slice_resid = 0;
} else {
rb_key = -NSEC_PER_SEC;
__cfqq = cfq_rb_first(st);
rb_key += __cfqq ? __cfqq->rb_key : now;
}
if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
new_cfqq = 0;
/*
* same position, nothing more to do
*/
if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
return;
cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
cfqq->service_tree = NULL;
}
left = 1;
parent = NULL;
cfqq->service_tree = st;
p = &st->rb.rb_node;
while (*p) {
parent = *p;
__cfqq = rb_entry(parent, struct cfq_queue, rb_node);
/*
* sort by key, that represents service time.
*/
if (rb_key < __cfqq->rb_key)
p = &parent->rb_left;
else {
p = &parent->rb_right;
left = 0;
}
}
if (left)
st->left = &cfqq->rb_node;
cfqq->rb_key = rb_key;
rb_link_node(&cfqq->rb_node, parent, p);
rb_insert_color(&cfqq->rb_node, &st->rb);
st->count++;
if (add_front || !new_cfqq)
return;
cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
}
static struct cfq_queue *
cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
sector_t sector, struct rb_node **ret_parent,
struct rb_node ***rb_link)
{
struct rb_node **p, *parent;
struct cfq_queue *cfqq = NULL;
parent = NULL;
p = &root->rb_node;
while (*p) {
struct rb_node **n;
parent = *p;
cfqq = rb_entry(parent, struct cfq_queue, p_node);
/*
* Sort strictly based on sector. Smallest to the left,
* largest to the right.
*/
if (sector > blk_rq_pos(cfqq->next_rq))
n = &(*p)->rb_right;
else if (sector < blk_rq_pos(cfqq->next_rq))
n = &(*p)->rb_left;
else
break;
p = n;
cfqq = NULL;
}
*ret_parent = parent;
if (rb_link)
*rb_link = p;
return cfqq;
}
static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
struct rb_node **p, *parent;
struct cfq_queue *__cfqq;
if (cfqq->p_root) {
rb_erase(&cfqq->p_node, cfqq->p_root);
cfqq->p_root = NULL;
}
if (cfq_class_idle(cfqq))
return;
if (!cfqq->next_rq)
return;
cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
__cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
blk_rq_pos(cfqq->next_rq), &parent, &p);
if (!__cfqq) {
rb_link_node(&cfqq->p_node, parent, p);
rb_insert_color(&cfqq->p_node, cfqq->p_root);
} else
cfqq->p_root = NULL;
}
/*
* Update cfqq's position in the service tree.
*/
static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
/*
* Resorting requires the cfqq to be on the RR list already.
*/
if (cfq_cfqq_on_rr(cfqq)) {
cfq_service_tree_add(cfqd, cfqq, 0);
cfq_prio_tree_add(cfqd, cfqq);
}
}
/*
* add to busy list of queues for service, trying to be fair in ordering
* the pending list according to last request service
*/
static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
BUG_ON(cfq_cfqq_on_rr(cfqq));
cfq_mark_cfqq_on_rr(cfqq);
cfqd->busy_queues++;
if (cfq_cfqq_sync(cfqq))
cfqd->busy_sync_queues++;
cfq_resort_rr_list(cfqd, cfqq);
}
/*
* Called when the cfqq no longer has requests pending, remove it from
* the service tree.
*/
static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
BUG_ON(!cfq_cfqq_on_rr(cfqq));
cfq_clear_cfqq_on_rr(cfqq);
if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
cfqq->service_tree = NULL;
}
if (cfqq->p_root) {
rb_erase(&cfqq->p_node, cfqq->p_root);
cfqq->p_root = NULL;
}
cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
BUG_ON(!cfqd->busy_queues);
cfqd->busy_queues--;
if (cfq_cfqq_sync(cfqq))
cfqd->busy_sync_queues--;
}
/*
* rb tree support functions
*/
static void cfq_del_rq_rb(struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
const int sync = rq_is_sync(rq);
BUG_ON(!cfqq->queued[sync]);
cfqq->queued[sync]--;
elv_rb_del(&cfqq->sort_list, rq);
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
/*
* Queue will be deleted from service tree when we actually
* expire it later. Right now just remove it from prio tree
* as it is empty.
*/
if (cfqq->p_root) {
rb_erase(&cfqq->p_node, cfqq->p_root);
cfqq->p_root = NULL;
}
}
}
static void cfq_add_rq_rb(struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
struct cfq_data *cfqd = cfqq->cfqd;
struct request *prev;
cfqq->queued[rq_is_sync(rq)]++;
elv_rb_add(&cfqq->sort_list, rq);
if (!cfq_cfqq_on_rr(cfqq))
cfq_add_cfqq_rr(cfqd, cfqq);
/*
* check if this request is a better next-serve candidate
*/
prev = cfqq->next_rq;
cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
/*
* adjust priority tree position, if ->next_rq changes
*/
if (prev != cfqq->next_rq)
cfq_prio_tree_add(cfqd, cfqq);
BUG_ON(!cfqq->next_rq);
}
static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
{
elv_rb_del(&cfqq->sort_list, rq);
cfqq->queued[rq_is_sync(rq)]--;
cfqg_stats_update_io_remove(RQ_CFQG(rq), req_op(rq), rq->cmd_flags);
cfq_add_rq_rb(rq);
cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
req_op(rq), rq->cmd_flags);
}
static struct request *
cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
{
struct task_struct *tsk = current;
struct cfq_io_cq *cic;
struct cfq_queue *cfqq;
cic = cfq_cic_lookup(cfqd, tsk->io_context);
if (!cic)
return NULL;
cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
if (cfqq)
return elv_rb_find(&cfqq->sort_list, bio_end_sector(bio));
return NULL;
}
static void cfq_activate_request(struct request_queue *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
cfqd->rq_in_driver++;
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
cfqd->rq_in_driver);
cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
}
static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
WARN_ON(!cfqd->rq_in_driver);
cfqd->rq_in_driver--;
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
cfqd->rq_in_driver);
}
static void cfq_remove_request(struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
if (cfqq->next_rq == rq)
cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
list_del_init(&rq->queuelist);
cfq_del_rq_rb(rq);
cfqq->cfqd->rq_queued--;
cfqg_stats_update_io_remove(RQ_CFQG(rq), req_op(rq), rq->cmd_flags);
if (rq->cmd_flags & REQ_PRIO) {
WARN_ON(!cfqq->prio_pending);
cfqq->prio_pending--;
}
}
static int cfq_merge(struct request_queue *q, struct request **req,
struct bio *bio)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct request *__rq;
__rq = cfq_find_rq_fmerge(cfqd, bio);
if (__rq && elv_bio_merge_ok(__rq, bio)) {
*req = __rq;
return ELEVATOR_FRONT_MERGE;
}
return ELEVATOR_NO_MERGE;
}
static void cfq_merged_request(struct request_queue *q, struct request *req,
int type)
{
if (type == ELEVATOR_FRONT_MERGE) {
struct cfq_queue *cfqq = RQ_CFQQ(req);
cfq_reposition_rq_rb(cfqq, req);
}
}
static void cfq_bio_merged(struct request_queue *q, struct request *req,
struct bio *bio)
{
cfqg_stats_update_io_merged(RQ_CFQG(req), bio_op(bio), bio->bi_rw);
}
static void
cfq_merged_requests(struct request_queue *q, struct request *rq,
struct request *next)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
struct cfq_data *cfqd = q->elevator->elevator_data;
/*
* reposition in fifo if next is older than rq
*/
if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
next->fifo_time < rq->fifo_time &&
cfqq == RQ_CFQQ(next)) {
list_move(&rq->queuelist, &next->queuelist);
rq->fifo_time = next->fifo_time;
}
if (cfqq->next_rq == next)
cfqq->next_rq = rq;
cfq_remove_request(next);
cfqg_stats_update_io_merged(RQ_CFQG(rq), req_op(next), next->cmd_flags);
cfqq = RQ_CFQQ(next);
/*
* all requests of this queue are merged to other queues, delete it
* from the service tree. If it's the active_queue,
* cfq_dispatch_requests() will choose to expire it or do idle
*/
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
cfqq != cfqd->active_queue)
cfq_del_cfqq_rr(cfqd, cfqq);
}
static int cfq_allow_bio_merge(struct request_queue *q, struct request *rq,
struct bio *bio)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_io_cq *cic;
struct cfq_queue *cfqq;
/*
* Disallow merge of a sync bio into an async request.
*/
if (cfq_bio_sync(bio) && !rq_is_sync(rq))
return false;
/*
* Lookup the cfqq that this bio will be queued with and allow
* merge only if rq is queued there.
*/
cic = cfq_cic_lookup(cfqd, current->io_context);
if (!cic)
return false;
cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
return cfqq == RQ_CFQQ(rq);
}
static int cfq_allow_rq_merge(struct request_queue *q, struct request *rq,
struct request *next)
{
return RQ_CFQQ(rq) == RQ_CFQQ(next);
}
static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
hrtimer_try_to_cancel(&cfqd->idle_slice_timer);
cfqg_stats_update_idle_time(cfqq->cfqg);
}
static void __cfq_set_active_queue(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
if (cfqq) {
cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
cfqd->serving_wl_class, cfqd->serving_wl_type);
cfqg_stats_update_avg_queue_size(cfqq->cfqg);
cfqq->slice_start = 0;
cfqq->dispatch_start = ktime_get_ns();
cfqq->allocated_slice = 0;
cfqq->slice_end = 0;
cfqq->slice_dispatch = 0;
cfqq->nr_sectors = 0;
cfq_clear_cfqq_wait_request(cfqq);
cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_must_alloc_slice(cfqq);
cfq_clear_cfqq_fifo_expire(cfqq);
cfq_mark_cfqq_slice_new(cfqq);
cfq_del_timer(cfqd, cfqq);
}
cfqd->active_queue = cfqq;
}
/*
* current cfqq expired its slice (or was too idle), select new one
*/
static void
__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
bool timed_out)
{
cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
if (cfq_cfqq_wait_request(cfqq))
cfq_del_timer(cfqd, cfqq);
cfq_clear_cfqq_wait_request(cfqq);
cfq_clear_cfqq_wait_busy(cfqq);
/*
* If this cfqq is shared between multiple processes, check to
* make sure that those processes are still issuing I/Os within
* the mean seek distance. If not, it may be time to break the
* queues apart again.
*/
if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
cfq_mark_cfqq_split_coop(cfqq);
/*
* store what was left of this slice, if the queue idled/timed out
*/
if (timed_out) {
if (cfq_cfqq_slice_new(cfqq))
cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
else
cfqq->slice_resid = cfqq->slice_end - ktime_get_ns();
cfq_log_cfqq(cfqd, cfqq, "resid=%lld", cfqq->slice_resid);
}
cfq_group_served(cfqd, cfqq->cfqg, cfqq);
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
cfq_del_cfqq_rr(cfqd, cfqq);
cfq_resort_rr_list(cfqd, cfqq);
if (cfqq == cfqd->active_queue)
cfqd->active_queue = NULL;
if (cfqd->active_cic) {
put_io_context(cfqd->active_cic->icq.ioc);
cfqd->active_cic = NULL;
}
}
static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
{
struct cfq_queue *cfqq = cfqd->active_queue;
if (cfqq)
__cfq_slice_expired(cfqd, cfqq, timed_out);
}
/*
* Get next queue for service. Unless we have a queue preemption,
* we'll simply select the first cfqq in the service tree.
*/
static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
{
struct cfq_rb_root *st = st_for(cfqd->serving_group,
cfqd->serving_wl_class, cfqd->serving_wl_type);
if (!cfqd->rq_queued)
return NULL;
/* There is nothing to dispatch */
if (!st)
return NULL;
if (RB_EMPTY_ROOT(&st->rb))
return NULL;
return cfq_rb_first(st);
}
static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
{
struct cfq_group *cfqg;
struct cfq_queue *cfqq;
int i, j;
struct cfq_rb_root *st;
if (!cfqd->rq_queued)
return NULL;
cfqg = cfq_get_next_cfqg(cfqd);
if (!cfqg)
return NULL;
for_each_cfqg_st(cfqg, i, j, st)
if ((cfqq = cfq_rb_first(st)) != NULL)
return cfqq;
return NULL;
}
/*
* Get and set a new active queue for service.
*/
static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
if (!cfqq)
cfqq = cfq_get_next_queue(cfqd);
__cfq_set_active_queue(cfqd, cfqq);
return cfqq;
}
static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
struct request *rq)
{
if (blk_rq_pos(rq) >= cfqd->last_position)
return blk_rq_pos(rq) - cfqd->last_position;
else
return cfqd->last_position - blk_rq_pos(rq);
}
static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct request *rq)
{
return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
}
static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
struct cfq_queue *cur_cfqq)
{
struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
struct rb_node *parent, *node;
struct cfq_queue *__cfqq;
sector_t sector = cfqd->last_position;
if (RB_EMPTY_ROOT(root))
return NULL;
/*
* First, if we find a request starting at the end of the last
* request, choose it.
*/
__cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
if (__cfqq)
return __cfqq;
/*
* If the exact sector wasn't found, the parent of the NULL leaf
* will contain the closest sector.
*/
__cfqq = rb_entry(parent, struct cfq_queue, p_node);
if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
return __cfqq;
if (blk_rq_pos(__cfqq->next_rq) < sector)
node = rb_next(&__cfqq->p_node);
else
node = rb_prev(&__cfqq->p_node);
if (!node)
return NULL;
__cfqq = rb_entry(node, struct cfq_queue, p_node);
if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
return __cfqq;
return NULL;
}
/*
* cfqd - obvious
* cur_cfqq - passed in so that we don't decide that the current queue is
* closely cooperating with itself.
*
* So, basically we're assuming that that cur_cfqq has dispatched at least
* one request, and that cfqd->last_position reflects a position on the disk
* associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
* assumption.
*/
static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
struct cfq_queue *cur_cfqq)
{
struct cfq_queue *cfqq;
if (cfq_class_idle(cur_cfqq))
return NULL;
if (!cfq_cfqq_sync(cur_cfqq))
return NULL;
if (CFQQ_SEEKY(cur_cfqq))
return NULL;
/*
* Don't search priority tree if it's the only queue in the group.
*/
if (cur_cfqq->cfqg->nr_cfqq == 1)
return NULL;
/*
* We should notice if some of the queues are cooperating, eg
* working closely on the same area of the disk. In that case,
* we can group them together and don't waste time idling.
*/
cfqq = cfqq_close(cfqd, cur_cfqq);
if (!cfqq)
return NULL;
/* If new queue belongs to different cfq_group, don't choose it */
if (cur_cfqq->cfqg != cfqq->cfqg)
return NULL;
/*
* It only makes sense to merge sync queues.
*/
if (!cfq_cfqq_sync(cfqq))
return NULL;
if (CFQQ_SEEKY(cfqq))
return NULL;
/*
* Do not merge queues of different priority classes
*/
if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
return NULL;
return cfqq;
}
/*
* Determine whether we should enforce idle window for this queue.
*/
static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
enum wl_class_t wl_class = cfqq_class(cfqq);
struct cfq_rb_root *st = cfqq->service_tree;
BUG_ON(!st);
BUG_ON(!st->count);
if (!cfqd->cfq_slice_idle)
return false;
/* We never do for idle class queues. */
if (wl_class == IDLE_WORKLOAD)
return false;
/* We do for queues that were marked with idle window flag. */
if (cfq_cfqq_idle_window(cfqq) &&
!(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
return true;
/*
* Otherwise, we do only if they are the last ones
* in their service tree.
*/
if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
!cfq_io_thinktime_big(cfqd, &st->ttime, false))
return true;
cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
return false;
}
static void cfq_arm_slice_timer(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq = cfqd->active_queue;
struct cfq_rb_root *st = cfqq->service_tree;
struct cfq_io_cq *cic;
u64 sl, group_idle = 0;
u64 now = ktime_get_ns();
/*
* SSD device without seek penalty, disable idling. But only do so
* for devices that support queuing, otherwise we still have a problem
* with sync vs async workloads.
*/
if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
return;
WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
WARN_ON(cfq_cfqq_slice_new(cfqq));
/*
* idle is disabled, either manually or by past process history
*/
if (!cfq_should_idle(cfqd, cfqq)) {
/* no queue idling. Check for group idling */
if (cfqd->cfq_group_idle)
group_idle = cfqd->cfq_group_idle;
else
return;
}
/*
* still active requests from this queue, don't idle
*/
if (cfqq->dispatched)
return;
/*
* task has exited, don't wait
*/
cic = cfqd->active_cic;
if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
return;
/*
* If our average think time is larger than the remaining time
* slice, then don't idle. This avoids overrunning the allotted
* time slice.
*/
if (sample_valid(cic->ttime.ttime_samples) &&
(cfqq->slice_end - now < cic->ttime.ttime_mean)) {
cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%llu",
cic->ttime.ttime_mean);
return;
}
/*
* There are other queues in the group or this is the only group and
* it has too big thinktime, don't do group idle.
*/
if (group_idle &&
(cfqq->cfqg->nr_cfqq > 1 ||
cfq_io_thinktime_big(cfqd, &st->ttime, true)))
return;
cfq_mark_cfqq_wait_request(cfqq);
if (group_idle)
sl = cfqd->cfq_group_idle;
else
sl = cfqd->cfq_slice_idle;
hrtimer_start(&cfqd->idle_slice_timer, ns_to_ktime(sl),
HRTIMER_MODE_REL);
cfqg_stats_set_start_idle_time(cfqq->cfqg);
cfq_log_cfqq(cfqd, cfqq, "arm_idle: %llu group_idle: %d", sl,
group_idle ? 1 : 0);
}
/*
* Move request from internal lists to the request queue dispatch list.
*/
static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq = RQ_CFQQ(rq);
cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
cfq_remove_request(rq);
cfqq->dispatched++;
(RQ_CFQG(rq))->dispatched++;
elv_dispatch_sort(q, rq);
cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
cfqq->nr_sectors += blk_rq_sectors(rq);
}
/*
* return expired entry, or NULL to just start from scratch in rbtree
*/
static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
{
struct request *rq = NULL;
if (cfq_cfqq_fifo_expire(cfqq))
return NULL;
cfq_mark_cfqq_fifo_expire(cfqq);
if (list_empty(&cfqq->fifo))
return NULL;
rq = rq_entry_fifo(cfqq->fifo.next);
if (ktime_get_ns() < rq->fifo_time)
rq = NULL;
cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
return rq;
}
static inline int
cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
const int base_rq = cfqd->cfq_slice_async_rq;
WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
}
/*
* Must be called with the queue_lock held.
*/
static int cfqq_process_refs(struct cfq_queue *cfqq)
{
int process_refs, io_refs;
io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
process_refs = cfqq->ref - io_refs;
BUG_ON(process_refs < 0);
return process_refs;
}
static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
{
int process_refs, new_process_refs;
struct cfq_queue *__cfqq;
/*
* If there are no process references on the new_cfqq, then it is
* unsafe to follow the ->new_cfqq chain as other cfqq's in the
* chain may have dropped their last reference (not just their
* last process reference).
*/
if (!cfqq_process_refs(new_cfqq))
return;
/* Avoid a circular list and skip interim queue merges */
while ((__cfqq = new_cfqq->new_cfqq)) {
if (__cfqq == cfqq)
return;
new_cfqq = __cfqq;
}
process_refs = cfqq_process_refs(cfqq);
new_process_refs = cfqq_process_refs(new_cfqq);
/*
* If the process for the cfqq has gone away, there is no
* sense in merging the queues.
*/
if (process_refs == 0 || new_process_refs == 0)
return;
/*
* Merge in the direction of the lesser amount of work.
*/
if (new_process_refs >= process_refs) {
cfqq->new_cfqq = new_cfqq;
new_cfqq->ref += process_refs;
} else {
new_cfqq->new_cfqq = cfqq;
cfqq->ref += new_process_refs;
}
}
static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
struct cfq_group *cfqg, enum wl_class_t wl_class)
{
struct cfq_queue *queue;
int i;
bool key_valid = false;
u64 lowest_key = 0;
enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
for (i = 0; i <= SYNC_WORKLOAD; ++i) {
/* select the one with lowest rb_key */
queue = cfq_rb_first(st_for(cfqg, wl_class, i));
if (queue &&
(!key_valid || queue->rb_key < lowest_key)) {
lowest_key = queue->rb_key;
cur_best = i;
key_valid = true;
}
}
return cur_best;
}
static void
choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
u64 slice;
unsigned count;
struct cfq_rb_root *st;
u64 group_slice;
enum wl_class_t original_class = cfqd->serving_wl_class;
u64 now = ktime_get_ns();
/* Choose next priority. RT > BE > IDLE */
if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
cfqd->serving_wl_class = RT_WORKLOAD;
else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
cfqd->serving_wl_class = BE_WORKLOAD;
else {
cfqd->serving_wl_class = IDLE_WORKLOAD;
cfqd->workload_expires = now + jiffies_to_nsecs(1);
return;
}
if (original_class != cfqd->serving_wl_class)
goto new_workload;
/*
* For RT and BE, we have to choose also the type
* (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
* expiration time
*/
st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
count = st->count;
/*
* check workload expiration, and that we still have other queues ready
*/
if (count && !(now > cfqd->workload_expires))
return;
new_workload:
/* otherwise select new workload type */
cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
cfqd->serving_wl_class);
st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
count = st->count;
/*
* the workload slice is computed as a fraction of target latency
* proportional to the number of queues in that workload, over
* all the queues in the same priority class
*/
group_slice = cfq_group_slice(cfqd, cfqg);
slice = div_u64(group_slice * count,
max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
cfqg)));
if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
u64 tmp;
/*
* Async queues are currently system wide. Just taking
* proportion of queues with-in same group will lead to higher
* async ratio system wide as generally root group is going
* to have higher weight. A more accurate thing would be to
* calculate system wide asnc/sync ratio.
*/
tmp = cfqd->cfq_target_latency *
cfqg_busy_async_queues(cfqd, cfqg);
tmp = div_u64(tmp, cfqd->busy_queues);
slice = min_t(u64, slice, tmp);
/* async workload slice is scaled down according to
* the sync/async slice ratio. */
slice = div64_u64(slice*cfqd->cfq_slice[0], cfqd->cfq_slice[1]);
} else
/* sync workload slice is at least 2 * cfq_slice_idle */
slice = max(slice, 2 * cfqd->cfq_slice_idle);
slice = max_t(u64, slice, CFQ_MIN_TT);
cfq_log(cfqd, "workload slice:%llu", slice);
cfqd->workload_expires = now + slice;
}
static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
struct cfq_group *cfqg;
if (RB_EMPTY_ROOT(&st->rb))
return NULL;
cfqg = cfq_rb_first_group(st);
update_min_vdisktime(st);
return cfqg;
}
static void cfq_choose_cfqg(struct cfq_data *cfqd)
{
struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
u64 now = ktime_get_ns();
cfqd->serving_group = cfqg;
/* Restore the workload type data */
if (cfqg->saved_wl_slice) {
cfqd->workload_expires = now + cfqg->saved_wl_slice;
cfqd->serving_wl_type = cfqg->saved_wl_type;
cfqd->serving_wl_class = cfqg->saved_wl_class;
} else
cfqd->workload_expires = now - 1;
choose_wl_class_and_type(cfqd, cfqg);
}
/*
* Select a queue for service. If we have a current active queue,
* check whether to continue servicing it, or retrieve and set a new one.
*/
static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq, *new_cfqq = NULL;
u64 now = ktime_get_ns();
cfqq = cfqd->active_queue;
if (!cfqq)
goto new_queue;
if (!cfqd->rq_queued)
return NULL;
/*
* We were waiting for group to get backlogged. Expire the queue
*/
if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
goto expire;
/*
* The active queue has run out of time, expire it and select new.
*/
if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
/*
* If slice had not expired at the completion of last request
* we might not have turned on wait_busy flag. Don't expire
* the queue yet. Allow the group to get backlogged.
*
* The very fact that we have used the slice, that means we
* have been idling all along on this queue and it should be
* ok to wait for this request to complete.
*/
if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
&& cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
cfqq = NULL;
goto keep_queue;
} else
goto check_group_idle;
}
/*
* The active queue has requests and isn't expired, allow it to
* dispatch.
*/
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
goto keep_queue;
/*
* If another queue has a request waiting within our mean seek
* distance, let it run. The expire code will check for close
* cooperators and put the close queue at the front of the service
* tree. If possible, merge the expiring queue with the new cfqq.
*/
new_cfqq = cfq_close_cooperator(cfqd, cfqq);
if (new_cfqq) {
if (!cfqq->new_cfqq)
cfq_setup_merge(cfqq, new_cfqq);
goto expire;
}
/*
* No requests pending. If the active queue still has requests in
* flight or is idling for a new request, allow either of these
* conditions to happen (or time out) before selecting a new queue.
*/
if (hrtimer_active(&cfqd->idle_slice_timer)) {
cfqq = NULL;
goto keep_queue;
}
/*
* This is a deep seek queue, but the device is much faster than
* the queue can deliver, don't idle
**/
if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
(cfq_cfqq_slice_new(cfqq) ||
(cfqq->slice_end - now > now - cfqq->slice_start))) {
cfq_clear_cfqq_deep(cfqq);
cfq_clear_cfqq_idle_window(cfqq);
}
if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
cfqq = NULL;
goto keep_queue;
}
/*
* If group idle is enabled and there are requests dispatched from
* this group, wait for requests to complete.
*/
check_group_idle:
if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
cfqq->cfqg->dispatched &&
!cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
cfqq = NULL;
goto keep_queue;
}
expire:
cfq_slice_expired(cfqd, 0);
new_queue:
/*
* Current queue expired. Check if we have to switch to a new
* service tree
*/
if (!new_cfqq)
cfq_choose_cfqg(cfqd);
cfqq = cfq_set_active_queue(cfqd, new_cfqq);
keep_queue:
return cfqq;
}
static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
{
int dispatched = 0;
while (cfqq->next_rq) {
cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
dispatched++;
}
BUG_ON(!list_empty(&cfqq->fifo));
/* By default cfqq is not expired if it is empty. Do it explicitly */
__cfq_slice_expired(cfqq->cfqd, cfqq, 0);
return dispatched;
}
/*
* Drain our current requests. Used for barriers and when switching
* io schedulers on-the-fly.
*/
static int cfq_forced_dispatch(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq;
int dispatched = 0;
/* Expire the timeslice of the current active queue first */
cfq_slice_expired(cfqd, 0);
while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
__cfq_set_active_queue(cfqd, cfqq);
dispatched += __cfq_forced_dispatch_cfqq(cfqq);
}
BUG_ON(cfqd->busy_queues);
cfq_log(cfqd, "forced_dispatch=%d", dispatched);
return dispatched;
}
static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
u64 now = ktime_get_ns();
/* the queue hasn't finished any request, can't estimate */
if (cfq_cfqq_slice_new(cfqq))
return true;
if (now + cfqd->cfq_slice_idle * cfqq->dispatched > cfqq->slice_end)
return true;
return false;
}
static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
unsigned int max_dispatch;
/*
* Drain async requests before we start sync IO
*/
if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
return false;
/*
* If this is an async queue and we have sync IO in flight, let it wait
*/
if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
return false;
max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
if (cfq_class_idle(cfqq))
max_dispatch = 1;
/*
* Does this cfqq already have too much IO in flight?
*/
if (cfqq->dispatched >= max_dispatch) {
bool promote_sync = false;
/*
* idle queue must always only have a single IO in flight
*/
if (cfq_class_idle(cfqq))
return false;
/*
* If there is only one sync queue
* we can ignore async queue here and give the sync
* queue no dispatch limit. The reason is a sync queue can
* preempt async queue, limiting the sync queue doesn't make
* sense. This is useful for aiostress test.
*/
if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
promote_sync = true;
/*
* We have other queues, don't allow more IO from this one
*/
if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
!promote_sync)
return false;
/*
* Sole queue user, no limit
*/
if (cfqd->busy_queues == 1 || promote_sync)
max_dispatch = -1;
else
/*
* Normally we start throttling cfqq when cfq_quantum/2
* requests have been dispatched. But we can drive
* deeper queue depths at the beginning of slice
* subjected to upper limit of cfq_quantum.
* */
max_dispatch = cfqd->cfq_quantum;
}
/*
* Async queues must wait a bit before being allowed dispatch.
* We also ramp up the dispatch depth gradually for async IO,
* based on the last sync IO we serviced
*/
if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
u64 last_sync = ktime_get_ns() - cfqd->last_delayed_sync;
unsigned int depth;
depth = div64_u64(last_sync, cfqd->cfq_slice[1]);
if (!depth && !cfqq->dispatched)
depth = 1;
if (depth < max_dispatch)
max_dispatch = depth;
}
/*
* If we're below the current max, allow a dispatch
*/
return cfqq->dispatched < max_dispatch;
}
/*
* Dispatch a request from cfqq, moving them to the request queue
* dispatch list.
*/
static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
struct request *rq;
BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
if (!cfq_may_dispatch(cfqd, cfqq))
return false;
/*
* follow expired path, else get first next available
*/
rq = cfq_check_fifo(cfqq);
if (!rq)
rq = cfqq->next_rq;
/*
* insert request into driver dispatch list
*/
cfq_dispatch_insert(cfqd->queue, rq);
if (!cfqd->active_cic) {
struct cfq_io_cq *cic = RQ_CIC(rq);
atomic_long_inc(&cic->icq.ioc->refcount);
cfqd->active_cic = cic;
}
return true;
}
/*
* Find the cfqq that we need to service and move a request from that to the
* dispatch list
*/
static int cfq_dispatch_requests(struct request_queue *q, int force)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq;
if (!cfqd->busy_queues)
return 0;
if (unlikely(force))
return cfq_forced_dispatch(cfqd);
cfqq = cfq_select_queue(cfqd);
if (!cfqq)
return 0;
/*
* Dispatch a request from this cfqq, if it is allowed
*/
if (!cfq_dispatch_request(cfqd, cfqq))
return 0;
cfqq->slice_dispatch++;
cfq_clear_cfqq_must_dispatch(cfqq);
/*
* expire an async queue immediately if it has used up its slice. idle
* queue always expire after 1 dispatch round.
*/
if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
cfq_class_idle(cfqq))) {
cfqq->slice_end = ktime_get_ns() + 1;
cfq_slice_expired(cfqd, 0);
}
cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
return 1;
}
/*
* task holds one reference to the queue, dropped when task exits. each rq
* in-flight on this queue also holds a reference, dropped when rq is freed.
*
* Each cfq queue took a reference on the parent group. Drop it now.
* queue lock must be held here.
*/
static void cfq_put_queue(struct cfq_queue *cfqq)
{
struct cfq_data *cfqd = cfqq->cfqd;
struct cfq_group *cfqg;
BUG_ON(cfqq->ref <= 0);
cfqq->ref--;
if (cfqq->ref)
return;
cfq_log_cfqq(cfqd, cfqq, "put_queue");
BUG_ON(rb_first(&cfqq->sort_list));
BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
cfqg = cfqq->cfqg;
if (unlikely(cfqd->active_queue == cfqq)) {
__cfq_slice_expired(cfqd, cfqq, 0);
cfq_schedule_dispatch(cfqd);
}
BUG_ON(cfq_cfqq_on_rr(cfqq));
kmem_cache_free(cfq_pool, cfqq);
cfqg_put(cfqg);
}
static void cfq_put_cooperator(struct cfq_queue *cfqq)
{
struct cfq_queue *__cfqq, *next;
/*
* If this queue was scheduled to merge with another queue, be
* sure to drop the reference taken on that queue (and others in
* the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
*/
__cfqq = cfqq->new_cfqq;
while (__cfqq) {
if (__cfqq == cfqq) {
WARN(1, "cfqq->new_cfqq loop detected\n");
break;
}
next = __cfqq->new_cfqq;
cfq_put_queue(__cfqq);
__cfqq = next;
}
}
static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
if (unlikely(cfqq == cfqd->active_queue)) {
__cfq_slice_expired(cfqd, cfqq, 0);
cfq_schedule_dispatch(cfqd);
}
cfq_put_cooperator(cfqq);
cfq_put_queue(cfqq);
}
static void cfq_init_icq(struct io_cq *icq)
{
struct cfq_io_cq *cic = icq_to_cic(icq);
cic->ttime.last_end_request = ktime_get_ns();
}
static void cfq_exit_icq(struct io_cq *icq)
{
struct cfq_io_cq *cic = icq_to_cic(icq);
struct cfq_data *cfqd = cic_to_cfqd(cic);
if (cic_to_cfqq(cic, false)) {
cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, false));
cic_set_cfqq(cic, NULL, false);
}
if (cic_to_cfqq(cic, true)) {
cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, true));
cic_set_cfqq(cic, NULL, true);
}
}
static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
{
struct task_struct *tsk = current;
int ioprio_class;
if (!cfq_cfqq_prio_changed(cfqq))
return;
ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
switch (ioprio_class) {
default:
printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
case IOPRIO_CLASS_NONE:
/*
* no prio set, inherit CPU scheduling settings
*/
cfqq->ioprio = task_nice_ioprio(tsk);
cfqq->ioprio_class = task_nice_ioclass(tsk);
break;
case IOPRIO_CLASS_RT:
cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
cfqq->ioprio_class = IOPRIO_CLASS_RT;
break;
case IOPRIO_CLASS_BE:
cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
cfqq->ioprio_class = IOPRIO_CLASS_BE;
break;
case IOPRIO_CLASS_IDLE:
cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
cfqq->ioprio = 7;
cfq_clear_cfqq_idle_window(cfqq);
break;
}
/*
* keep track of original prio settings in case we have to temporarily
* elevate the priority of this queue
*/
cfqq->org_ioprio = cfqq->ioprio;
cfqq->org_ioprio_class = cfqq->ioprio_class;
cfq_clear_cfqq_prio_changed(cfqq);
}
static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
{
int ioprio = cic->icq.ioc->ioprio;
struct cfq_data *cfqd = cic_to_cfqd(cic);
struct cfq_queue *cfqq;
/*
* Check whether ioprio has changed. The condition may trigger
* spuriously on a newly created cic but there's no harm.
*/
if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
return;
cfqq = cic_to_cfqq(cic, false);
if (cfqq) {
cfq_put_queue(cfqq);
cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio);
cic_set_cfqq(cic, cfqq, false);
}
cfqq = cic_to_cfqq(cic, true);
if (cfqq)
cfq_mark_cfqq_prio_changed(cfqq);
cic->ioprio = ioprio;
}
static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
pid_t pid, bool is_sync)
{
RB_CLEAR_NODE(&cfqq->rb_node);
RB_CLEAR_NODE(&cfqq->p_node);
INIT_LIST_HEAD(&cfqq->fifo);
cfqq->ref = 0;
cfqq->cfqd = cfqd;
cfq_mark_cfqq_prio_changed(cfqq);
if (is_sync) {
if (!cfq_class_idle(cfqq))
cfq_mark_cfqq_idle_window(cfqq);
cfq_mark_cfqq_sync(cfqq);
}
cfqq->pid = pid;
}
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
{
struct cfq_data *cfqd = cic_to_cfqd(cic);
struct cfq_queue *cfqq;
uint64_t serial_nr;
rcu_read_lock();
serial_nr = bio_blkcg(bio)->css.serial_nr;
rcu_read_unlock();
/*
* Check whether blkcg has changed. The condition may trigger
* spuriously on a newly created cic but there's no harm.
*/
if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
return;
/*
* Drop reference to queues. New queues will be assigned in new
* group upon arrival of fresh requests.
*/
cfqq = cic_to_cfqq(cic, false);
if (cfqq) {
cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
cic_set_cfqq(cic, NULL, false);
cfq_put_queue(cfqq);
}
cfqq = cic_to_cfqq(cic, true);
if (cfqq) {
cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
cic_set_cfqq(cic, NULL, true);
cfq_put_queue(cfqq);
}
cic->blkcg_serial_nr = serial_nr;
}
#else
static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
#endif /* CONFIG_CFQ_GROUP_IOSCHED */
static struct cfq_queue **
cfq_async_queue_prio(struct cfq_group *cfqg, int ioprio_class, int ioprio)
{
switch (ioprio_class) {
case IOPRIO_CLASS_RT:
return &cfqg->async_cfqq[0][ioprio];
case IOPRIO_CLASS_NONE:
ioprio = IOPRIO_NORM;
/* fall through */
case IOPRIO_CLASS_BE:
return &cfqg->async_cfqq[1][ioprio];
case IOPRIO_CLASS_IDLE:
return &cfqg->async_idle_cfqq;
default:
BUG();
}
}
static struct cfq_queue *
cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
struct bio *bio)
{
int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
struct cfq_queue **async_cfqq = NULL;
struct cfq_queue *cfqq;
struct cfq_group *cfqg;
rcu_read_lock();
cfqg = cfq_lookup_cfqg(cfqd, bio_blkcg(bio));
if (!cfqg) {
cfqq = &cfqd->oom_cfqq;
goto out;
}
if (!is_sync) {
if (!ioprio_valid(cic->ioprio)) {
struct task_struct *tsk = current;
ioprio = task_nice_ioprio(tsk);
ioprio_class = task_nice_ioclass(tsk);
}
async_cfqq = cfq_async_queue_prio(cfqg, ioprio_class, ioprio);
cfqq = *async_cfqq;
if (cfqq)
goto out;
}
cfqq = kmem_cache_alloc_node(cfq_pool, GFP_NOWAIT | __GFP_ZERO,
cfqd->queue->node);
if (!cfqq) {
cfqq = &cfqd->oom_cfqq;
goto out;
}
cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
cfq_init_prio_data(cfqq, cic);
cfq_link_cfqq_cfqg(cfqq, cfqg);
cfq_log_cfqq(cfqd, cfqq, "alloced");
if (async_cfqq) {
/* a new async queue is created, pin and remember */
cfqq->ref++;
*async_cfqq = cfqq;
}
out:
cfqq->ref++;
rcu_read_unlock();
return cfqq;
}
static void
__cfq_update_io_thinktime(struct cfq_ttime *ttime, u64 slice_idle)
{
u64 elapsed = ktime_get_ns() - ttime->last_end_request;
elapsed = min(elapsed, 2UL * slice_idle);
ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed, 8);
ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
ttime->ttime_samples);
}
static void
cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct cfq_io_cq *cic)
{
if (cfq_cfqq_sync(cfqq)) {
__cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
__cfq_update_io_thinktime(&cfqq->service_tree->ttime,
cfqd->cfq_slice_idle);
}
#ifdef CONFIG_CFQ_GROUP_IOSCHED
__cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
#endif
}
static void
cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct request *rq)
{
sector_t sdist = 0;
sector_t n_sec = blk_rq_sectors(rq);
if (cfqq->last_request_pos) {
if (cfqq->last_request_pos < blk_rq_pos(rq))
sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
else
sdist = cfqq->last_request_pos - blk_rq_pos(rq);
}
cfqq->seek_history <<= 1;
if (blk_queue_nonrot(cfqd->queue))
cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
else
cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
}
/*
* Disable idle window if the process thinks too long or seeks so much that
* it doesn't matter
*/
static void
cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct cfq_io_cq *cic)
{
int old_idle, enable_idle;
/*
* Don't idle for async or idle io prio class
*/
if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
return;
enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
if (cfqq->queued[0] + cfqq->queued[1] >= 4)
cfq_mark_cfqq_deep(cfqq);
if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
enable_idle = 0;
else if (!atomic_read(&cic->icq.ioc->active_ref) ||
!cfqd->cfq_slice_idle ||
(!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
enable_idle = 0;
else if (sample_valid(cic->ttime.ttime_samples)) {
if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
enable_idle = 0;
else
enable_idle = 1;
}
if (old_idle != enable_idle) {
cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
if (enable_idle)
cfq_mark_cfqq_idle_window(cfqq);
else
cfq_clear_cfqq_idle_window(cfqq);
}
}
/*
* Check if new_cfqq should preempt the currently active queue. Return 0 for
* no or if we aren't sure, a 1 will cause a preempt.
*/
static bool
cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
struct request *rq)
{
struct cfq_queue *cfqq;
cfqq = cfqd->active_queue;
if (!cfqq)
return false;
if (cfq_class_idle(new_cfqq))
return false;
if (cfq_class_idle(cfqq))
return true;
/*
* Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
*/
if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
return false;
/*
* if the new request is sync, but the currently running queue is
* not, let the sync request have priority.
*/
if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
return true;
/*
* Treat ancestors of current cgroup the same way as current cgroup.
* For anybody else we disallow preemption to guarantee service
* fairness among cgroups.
*/
if (!cfqg_is_descendant(cfqq->cfqg, new_cfqq->cfqg))
return false;
if (cfq_slice_used(cfqq))
return true;
/*
* Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
*/
if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
return true;
WARN_ON_ONCE(cfqq->ioprio_class != new_cfqq->ioprio_class);
/* Allow preemption only if we are idling on sync-noidle tree */
if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
RB_EMPTY_ROOT(&cfqq->sort_list))
return true;
/*
* So both queues are sync. Let the new request get disk time if
* it's a metadata request and the current queue is doing regular IO.
*/
if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
return true;
/* An idle queue should not be idle now for some reason */
if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
return true;
if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
return false;
/*
* if this request is as-good as one we would expect from the
* current cfqq, let it preempt
*/
if (cfq_rq_close(cfqd, cfqq, rq))
return true;
return false;
}
/*
* cfqq preempts the active queue. if we allowed preempt with no slice left,
* let it have half of its nominal slice.
*/
static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
cfq_log_cfqq(cfqd, cfqq, "preempt");
cfq_slice_expired(cfqd, 1);
/*
* workload type is changed, don't save slice, otherwise preempt
* doesn't happen
*/
if (old_type != cfqq_type(cfqq))
cfqq->cfqg->saved_wl_slice = 0;
/*
* Put the new queue at the front of the of the current list,
* so we know that it will be selected next.
*/
BUG_ON(!cfq_cfqq_on_rr(cfqq));
cfq_service_tree_add(cfqd, cfqq, 1);
cfqq->slice_end = 0;
cfq_mark_cfqq_slice_new(cfqq);
}
/*
* Called when a new fs request (rq) is added (to cfqq). Check if there's
* something we should do about it
*/
static void
cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct request *rq)
{
struct cfq_io_cq *cic = RQ_CIC(rq);
cfqd->rq_queued++;
if (rq->cmd_flags & REQ_PRIO)
cfqq->prio_pending++;
cfq_update_io_thinktime(cfqd, cfqq, cic);
cfq_update_io_seektime(cfqd, cfqq, rq);
cfq_update_idle_window(cfqd, cfqq, cic);
cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
if (cfqq == cfqd->active_queue) {
/*
* Remember that we saw a request from this process, but
* don't start queuing just yet. Otherwise we risk seeing lots
* of tiny requests, because we disrupt the normal plugging
* and merging. If the request is already larger than a single
* page, let it rip immediately. For that case we assume that
* merging is already done. Ditto for a busy system that
* has other work pending, don't risk delaying until the
* idle timer unplug to continue working.
*/
if (cfq_cfqq_wait_request(cfqq)) {
if (blk_rq_bytes(rq) > PAGE_SIZE ||
cfqd->busy_queues > 1) {
cfq_del_timer(cfqd, cfqq);
cfq_clear_cfqq_wait_request(cfqq);
__blk_run_queue(cfqd->queue);
} else {
cfqg_stats_update_idle_time(cfqq->cfqg);
cfq_mark_cfqq_must_dispatch(cfqq);
}
}
} else if (cfq_should_preempt(cfqd, cfqq, rq)) {
/*
* not the active queue - expire current slice if it is
* idle and has expired it's mean thinktime or this new queue
* has some old slice time left and is of higher priority or
* this new queue is RT and the current one is BE
*/
cfq_preempt_queue(cfqd, cfqq);
__blk_run_queue(cfqd->queue);
}
}
static void cfq_insert_request(struct request_queue *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq = RQ_CFQQ(rq);
cfq_log_cfqq(cfqd, cfqq, "insert_request");
cfq_init_prio_data(cfqq, RQ_CIC(rq));
rq->fifo_time = ktime_get_ns() + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
list_add_tail(&rq->queuelist, &cfqq->fifo);
cfq_add_rq_rb(rq);
cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group, req_op(rq),
rq->cmd_flags);
cfq_rq_enqueued(cfqd, cfqq, rq);
}
/*
* Update hw_tag based on peak queue depth over 50 samples under
* sufficient load.
*/
static void cfq_update_hw_tag(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq = cfqd->active_queue;
if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
if (cfqd->hw_tag == 1)
return;
if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
return;
/*
* If active queue hasn't enough requests and can idle, cfq might not
* dispatch sufficient requests to hardware. Don't zero hw_tag in this
* case
*/
if (cfqq && cfq_cfqq_idle_window(cfqq) &&
cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
return;
if (cfqd->hw_tag_samples++ < 50)
return;
if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
cfqd->hw_tag = 1;
else
cfqd->hw_tag = 0;
}
static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
struct cfq_io_cq *cic = cfqd->active_cic;
u64 now = ktime_get_ns();
/* If the queue already has requests, don't wait */
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
return false;
/* If there are other queues in the group, don't wait */
if (cfqq->cfqg->nr_cfqq > 1)
return false;
/* the only queue in the group, but think time is big */
if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
return false;
if (cfq_slice_used(cfqq))
return true;
/* if slice left is less than think time, wait busy */
if (cic && sample_valid(cic->ttime.ttime_samples)
&& (cfqq->slice_end - now < cic->ttime.ttime_mean))
return true;
/*
* If think times is less than a jiffy than ttime_mean=0 and above
* will not be true. It might happen that slice has not expired yet
* but will expire soon (4-5 ns) during select_queue(). To cover the
* case where think time is less than a jiffy, mark the queue wait
* busy if only 1 jiffy is left in the slice.
*/
if (cfqq->slice_end - now <= jiffies_to_nsecs(1))
return true;
return false;
}
static void cfq_completed_request(struct request_queue *q, struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
struct cfq_data *cfqd = cfqq->cfqd;
const int sync = rq_is_sync(rq);
u64 now = ktime_get_ns();
cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
!!(rq->cmd_flags & REQ_NOIDLE));
cfq_update_hw_tag(cfqd);
WARN_ON(!cfqd->rq_in_driver);
WARN_ON(!cfqq->dispatched);
cfqd->rq_in_driver--;
cfqq->dispatched--;
(RQ_CFQG(rq))->dispatched--;
cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
rq_io_start_time_ns(rq), req_op(rq),
rq->cmd_flags);
cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
if (sync) {
struct cfq_rb_root *st;
RQ_CIC(rq)->ttime.last_end_request = now;
if (cfq_cfqq_on_rr(cfqq))
st = cfqq->service_tree;
else
st = st_for(cfqq->cfqg, cfqq_class(cfqq),
cfqq_type(cfqq));
st->ttime.last_end_request = now;
/*
* We have to do this check in jiffies since start_time is in
* jiffies and it is not trivial to convert to ns. If
* cfq_fifo_expire[1] ever comes close to 1 jiffie, this test
* will become problematic but so far we are fine (the default
* is 128 ms).
*/
if (!time_after(rq->start_time +
nsecs_to_jiffies(cfqd->cfq_fifo_expire[1]),
jiffies))
cfqd->last_delayed_sync = now;
}
#ifdef CONFIG_CFQ_GROUP_IOSCHED
cfqq->cfqg->ttime.last_end_request = now;
#endif
/*
* If this is the active queue, check if it needs to be expired,
* or if we want to idle in case it has no pending requests.
*/
if (cfqd->active_queue == cfqq) {
const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
if (cfq_cfqq_slice_new(cfqq)) {
cfq_set_prio_slice(cfqd, cfqq);
cfq_clear_cfqq_slice_new(cfqq);
}
/*
* Should we wait for next request to come in before we expire
* the queue.
*/
if (cfq_should_wait_busy(cfqd, cfqq)) {
u64 extend_sl = cfqd->cfq_slice_idle;
if (!cfqd->cfq_slice_idle)
extend_sl = cfqd->cfq_group_idle;
cfqq->slice_end = now + extend_sl;
cfq_mark_cfqq_wait_busy(cfqq);
cfq_log_cfqq(cfqd, cfqq, "will busy wait");
}
/*
* Idling is not enabled on:
* - expired queues
* - idle-priority queues
* - async queues
* - queues with still some requests queued
* - when there is a close cooperator
*/
if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
cfq_slice_expired(cfqd, 1);
else if (sync && cfqq_empty &&
!cfq_close_cooperator(cfqd, cfqq)) {
cfq_arm_slice_timer(cfqd);
}
}
if (!cfqd->rq_in_driver)
cfq_schedule_dispatch(cfqd);
}
static void cfqq_boost_on_prio(struct cfq_queue *cfqq, int op_flags)
{
/*
* If REQ_PRIO is set, boost class and prio level, if it's below
* BE/NORM. If prio is not set, restore the potentially boosted
* class/prio level.
*/
if (!(op_flags & REQ_PRIO)) {
cfqq->ioprio_class = cfqq->org_ioprio_class;
cfqq->ioprio = cfqq->org_ioprio;
} else {
if (cfq_class_idle(cfqq))
cfqq->ioprio_class = IOPRIO_CLASS_BE;
if (cfqq->ioprio > IOPRIO_NORM)
cfqq->ioprio = IOPRIO_NORM;
}
}
static inline int __cfq_may_queue(struct cfq_queue *cfqq)
{
if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
cfq_mark_cfqq_must_alloc_slice(cfqq);
return ELV_MQUEUE_MUST;
}
return ELV_MQUEUE_MAY;
}
static int cfq_may_queue(struct request_queue *q, int op, int op_flags)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct task_struct *tsk = current;
struct cfq_io_cq *cic;
struct cfq_queue *cfqq;
/*
* don't force setup of a queue from here, as a call to may_queue
* does not necessarily imply that a request actually will be queued.
* so just lookup a possibly existing queue, or return 'may queue'
* if that fails
*/
cic = cfq_cic_lookup(cfqd, tsk->io_context);
if (!cic)
return ELV_MQUEUE_MAY;
cfqq = cic_to_cfqq(cic, rw_is_sync(op, op_flags));
if (cfqq) {
cfq_init_prio_data(cfqq, cic);
cfqq_boost_on_prio(cfqq, op_flags);
return __cfq_may_queue(cfqq);
}
return ELV_MQUEUE_MAY;
}
/*
* queue lock held here
*/
static void cfq_put_request(struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
if (cfqq) {
const int rw = rq_data_dir(rq);
BUG_ON(!cfqq->allocated[rw]);
cfqq->allocated[rw]--;
/* Put down rq reference on cfqg */
cfqg_put(RQ_CFQG(rq));
rq->elv.priv[0] = NULL;
rq->elv.priv[1] = NULL;
cfq_put_queue(cfqq);
}
}
static struct cfq_queue *
cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
struct cfq_queue *cfqq)
{
cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
cic_set_cfqq(cic, cfqq->new_cfqq, 1);
cfq_mark_cfqq_coop(cfqq->new_cfqq);
cfq_put_queue(cfqq);
return cic_to_cfqq(cic, 1);
}
/*
* Returns NULL if a new cfqq should be allocated, or the old cfqq if this
* was the last process referring to said cfqq.
*/
static struct cfq_queue *
split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
{
if (cfqq_process_refs(cfqq) == 1) {
cfqq->pid = current->pid;
cfq_clear_cfqq_coop(cfqq);
cfq_clear_cfqq_split_coop(cfqq);
return cfqq;
}
cic_set_cfqq(cic, NULL, 1);
cfq_put_cooperator(cfqq);
cfq_put_queue(cfqq);
return NULL;
}
/*
* Allocate cfq data structures associated with this request.
*/
static int
cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
gfp_t gfp_mask)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
const int rw = rq_data_dir(rq);
const bool is_sync = rq_is_sync(rq);
struct cfq_queue *cfqq;
spin_lock_irq(q->queue_lock);
check_ioprio_changed(cic, bio);
check_blkcg_changed(cic, bio);
new_queue:
cfqq = cic_to_cfqq(cic, is_sync);
if (!cfqq || cfqq == &cfqd->oom_cfqq) {
if (cfqq)
cfq_put_queue(cfqq);
cfqq = cfq_get_queue(cfqd, is_sync, cic, bio);
cic_set_cfqq(cic, cfqq, is_sync);
} else {
/*
* If the queue was seeky for too long, break it apart.
*/
if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
cfqq = split_cfqq(cic, cfqq);
if (!cfqq)
goto new_queue;
}
/*
* Check to see if this queue is scheduled to merge with
* another, closely cooperating queue. The merging of
* queues happens here as it must be done in process context.
* The reference on new_cfqq was taken in merge_cfqqs.
*/
if (cfqq->new_cfqq)
cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
}
cfqq->allocated[rw]++;
cfqq->ref++;
cfqg_get(cfqq->cfqg);
rq->elv.priv[0] = cfqq;
rq->elv.priv[1] = cfqq->cfqg;
spin_unlock_irq(q->queue_lock);
return 0;
}
static void cfq_kick_queue(struct work_struct *work)
{
struct cfq_data *cfqd =
container_of(work, struct cfq_data, unplug_work);
struct request_queue *q = cfqd->queue;
spin_lock_irq(q->queue_lock);
__blk_run_queue(cfqd->queue);
spin_unlock_irq(q->queue_lock);
}
/*
* Timer running if the active_queue is currently idling inside its time slice
*/
static enum hrtimer_restart cfq_idle_slice_timer(struct hrtimer *timer)
{
struct cfq_data *cfqd = container_of(timer, struct cfq_data,
idle_slice_timer);
struct cfq_queue *cfqq;
unsigned long flags;
int timed_out = 1;
cfq_log(cfqd, "idle timer fired");
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
cfqq = cfqd->active_queue;
if (cfqq) {
timed_out = 0;
/*
* We saw a request before the queue expired, let it through
*/
if (cfq_cfqq_must_dispatch(cfqq))
goto out_kick;
/*
* expired
*/
if (cfq_slice_used(cfqq))
goto expire;
/*
* only expire and reinvoke request handler, if there are
* other queues with pending requests
*/
if (!cfqd->busy_queues)
goto out_cont;
/*
* not expired and it has a request pending, let it dispatch
*/
if (!RB_EMPTY_ROOT(&cfqq->sort_list))
goto out_kick;
/*
* Queue depth flag is reset only when the idle didn't succeed
*/
cfq_clear_cfqq_deep(cfqq);
}
expire:
cfq_slice_expired(cfqd, timed_out);
out_kick:
cfq_schedule_dispatch(cfqd);
out_cont:
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
return HRTIMER_NORESTART;
}
static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
{
hrtimer_cancel(&cfqd->idle_slice_timer);
cancel_work_sync(&cfqd->unplug_work);
}
static void cfq_exit_queue(struct elevator_queue *e)
{
struct cfq_data *cfqd = e->elevator_data;
struct request_queue *q = cfqd->queue;
cfq_shutdown_timer_wq(cfqd);
spin_lock_irq(q->queue_lock);
if (cfqd->active_queue)
__cfq_slice_expired(cfqd, cfqd->active_queue, 0);
spin_unlock_irq(q->queue_lock);
cfq_shutdown_timer_wq(cfqd);
#ifdef CONFIG_CFQ_GROUP_IOSCHED
blkcg_deactivate_policy(q, &blkcg_policy_cfq);
#else
kfree(cfqd->root_group);
#endif
kfree(cfqd);
}
static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
{
struct cfq_data *cfqd;
struct blkcg_gq *blkg __maybe_unused;
int i, ret;
struct elevator_queue *eq;
eq = elevator_alloc(q, e);
if (!eq)
return -ENOMEM;
cfqd = kzalloc_node(sizeof(*cfqd), GFP_KERNEL, q->node);
if (!cfqd) {
kobject_put(&eq->kobj);
return -ENOMEM;
}
eq->elevator_data = cfqd;
cfqd->queue = q;
spin_lock_irq(q->queue_lock);
q->elevator = eq;
spin_unlock_irq(q->queue_lock);
/* Init root service tree */
cfqd->grp_service_tree = CFQ_RB_ROOT;
/* Init root group and prefer root group over other groups by default */
#ifdef CONFIG_CFQ_GROUP_IOSCHED
ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
if (ret)
goto out_free;
cfqd->root_group = blkg_to_cfqg(q->root_blkg);
#else
ret = -ENOMEM;
cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
GFP_KERNEL, cfqd->queue->node);
if (!cfqd->root_group)
goto out_free;
cfq_init_cfqg_base(cfqd->root_group);
cfqd->root_group->weight = 2 * CFQ_WEIGHT_LEGACY_DFL;
cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_LEGACY_DFL;
#endif
/*
* Not strictly needed (since RB_ROOT just clears the node and we
* zeroed cfqd on alloc), but better be safe in case someone decides
* to add magic to the rb code
*/
for (i = 0; i < CFQ_PRIO_LISTS; i++)
cfqd->prio_trees[i] = RB_ROOT;
/*
* Our fallback cfqq if cfq_get_queue() runs into OOM issues.
* Grab a permanent reference to it, so that the normal code flow
* will not attempt to free it. oom_cfqq is linked to root_group
* but shouldn't hold a reference as it'll never be unlinked. Lose
* the reference from linking right away.
*/
cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
cfqd->oom_cfqq.ref++;
spin_lock_irq(q->queue_lock);
cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
cfqg_put(cfqd->root_group);
spin_unlock_irq(q->queue_lock);
hrtimer_init(&cfqd->idle_slice_timer, CLOCK_MONOTONIC,
HRTIMER_MODE_REL);
cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
cfqd->cfq_quantum = cfq_quantum;
cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
cfqd->cfq_back_max = cfq_back_max;
cfqd->cfq_back_penalty = cfq_back_penalty;
cfqd->cfq_slice[0] = cfq_slice_async;
cfqd->cfq_slice[1] = cfq_slice_sync;
cfqd->cfq_target_latency = cfq_target_latency;
cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
cfqd->cfq_slice_idle = cfq_slice_idle;
cfqd->cfq_group_idle = cfq_group_idle;
cfqd->cfq_latency = 1;
cfqd->hw_tag = -1;
/*
* we optimistically start assuming sync ops weren't delayed in last
* second, in order to have larger depth for async operations.
*/
cfqd->last_delayed_sync = ktime_get_ns() - NSEC_PER_SEC;
return 0;
out_free:
kfree(cfqd);
kobject_put(&eq->kobj);
return ret;
}
static void cfq_registered_queue(struct request_queue *q)
{
struct elevator_queue *e = q->elevator;
struct cfq_data *cfqd = e->elevator_data;
/*
* Default to IOPS mode with no idling for SSDs
*/
if (blk_queue_nonrot(q))
cfqd->cfq_slice_idle = 0;
}
/*
* sysfs parts below -->
*/
static ssize_t
cfq_var_show(unsigned int var, char *page)
{
return sprintf(page, "%u\n", var);
}
static ssize_t
cfq_var_store(unsigned int *var, const char *page, size_t count)
{
char *p = (char *) page;
*var = simple_strtoul(p, &p, 10);
return count;
}
#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
static ssize_t __FUNC(struct elevator_queue *e, char *page) \
{ \
struct cfq_data *cfqd = e->elevator_data; \
u64 __data = __VAR; \
if (__CONV) \
__data = div_u64(__data, NSEC_PER_MSEC); \
return cfq_var_show(__data, (page)); \
}
SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
#undef SHOW_FUNCTION
#define USEC_SHOW_FUNCTION(__FUNC, __VAR) \
static ssize_t __FUNC(struct elevator_queue *e, char *page) \
{ \
struct cfq_data *cfqd = e->elevator_data; \
u64 __data = __VAR; \
__data = div_u64(__data, NSEC_PER_USEC); \
return cfq_var_show(__data, (page)); \
}
USEC_SHOW_FUNCTION(cfq_slice_idle_us_show, cfqd->cfq_slice_idle);
USEC_SHOW_FUNCTION(cfq_group_idle_us_show, cfqd->cfq_group_idle);
USEC_SHOW_FUNCTION(cfq_slice_sync_us_show, cfqd->cfq_slice[1]);
USEC_SHOW_FUNCTION(cfq_slice_async_us_show, cfqd->cfq_slice[0]);
USEC_SHOW_FUNCTION(cfq_target_latency_us_show, cfqd->cfq_target_latency);
#undef USEC_SHOW_FUNCTION
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
{ \
struct cfq_data *cfqd = e->elevator_data; \
unsigned int __data; \
int ret = cfq_var_store(&__data, (page), count); \
if (__data < (MIN)) \
__data = (MIN); \
else if (__data > (MAX)) \
__data = (MAX); \
if (__CONV) \
*(__PTR) = (u64)__data * NSEC_PER_MSEC; \
else \
*(__PTR) = __data; \
return ret; \
}
STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
UINT_MAX, 1);
STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
UINT_MAX, 1);
STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
UINT_MAX, 0);
STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
UINT_MAX, 0);
STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
#undef STORE_FUNCTION
#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \
static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
{ \
struct cfq_data *cfqd = e->elevator_data; \
unsigned int __data; \
int ret = cfq_var_store(&__data, (page), count); \
if (__data < (MIN)) \
__data = (MIN); \
else if (__data > (MAX)) \
__data = (MAX); \
*(__PTR) = (u64)__data * NSEC_PER_USEC; \
return ret; \
}
USEC_STORE_FUNCTION(cfq_slice_idle_us_store, &cfqd->cfq_slice_idle, 0, UINT_MAX);
USEC_STORE_FUNCTION(cfq_group_idle_us_store, &cfqd->cfq_group_idle, 0, UINT_MAX);
USEC_STORE_FUNCTION(cfq_slice_sync_us_store, &cfqd->cfq_slice[1], 1, UINT_MAX);
USEC_STORE_FUNCTION(cfq_slice_async_us_store, &cfqd->cfq_slice[0], 1, UINT_MAX);
USEC_STORE_FUNCTION(cfq_target_latency_us_store, &cfqd->cfq_target_latency, 1, UINT_MAX);
#undef USEC_STORE_FUNCTION
#define CFQ_ATTR(name) \
__ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
static struct elv_fs_entry cfq_attrs[] = {
CFQ_ATTR(quantum),
CFQ_ATTR(fifo_expire_sync),
CFQ_ATTR(fifo_expire_async),
CFQ_ATTR(back_seek_max),
CFQ_ATTR(back_seek_penalty),
CFQ_ATTR(slice_sync),
CFQ_ATTR(slice_sync_us),
CFQ_ATTR(slice_async),
CFQ_ATTR(slice_async_us),
CFQ_ATTR(slice_async_rq),
CFQ_ATTR(slice_idle),
CFQ_ATTR(slice_idle_us),
CFQ_ATTR(group_idle),
CFQ_ATTR(group_idle_us),
CFQ_ATTR(low_latency),
CFQ_ATTR(target_latency),
CFQ_ATTR(target_latency_us),
__ATTR_NULL
};
static struct elevator_type iosched_cfq = {
.ops = {
.elevator_merge_fn = cfq_merge,
.elevator_merged_fn = cfq_merged_request,
.elevator_merge_req_fn = cfq_merged_requests,
.elevator_allow_bio_merge_fn = cfq_allow_bio_merge,
.elevator_allow_rq_merge_fn = cfq_allow_rq_merge,
.elevator_bio_merged_fn = cfq_bio_merged,
.elevator_dispatch_fn = cfq_dispatch_requests,
.elevator_add_req_fn = cfq_insert_request,
.elevator_activate_req_fn = cfq_activate_request,
.elevator_deactivate_req_fn = cfq_deactivate_request,
.elevator_completed_req_fn = cfq_completed_request,
.elevator_former_req_fn = elv_rb_former_request,
.elevator_latter_req_fn = elv_rb_latter_request,
.elevator_init_icq_fn = cfq_init_icq,
.elevator_exit_icq_fn = cfq_exit_icq,
.elevator_set_req_fn = cfq_set_request,
.elevator_put_req_fn = cfq_put_request,
.elevator_may_queue_fn = cfq_may_queue,
.elevator_init_fn = cfq_init_queue,
.elevator_exit_fn = cfq_exit_queue,
.elevator_registered_fn = cfq_registered_queue,
},
.icq_size = sizeof(struct cfq_io_cq),
.icq_align = __alignof__(struct cfq_io_cq),
.elevator_attrs = cfq_attrs,
.elevator_name = "cfq",
.elevator_owner = THIS_MODULE,
};
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static struct blkcg_policy blkcg_policy_cfq = {
.dfl_cftypes = cfq_blkcg_files,
.legacy_cftypes = cfq_blkcg_legacy_files,
.cpd_alloc_fn = cfq_cpd_alloc,
.cpd_init_fn = cfq_cpd_init,
.cpd_free_fn = cfq_cpd_free,
.cpd_bind_fn = cfq_cpd_bind,
.pd_alloc_fn = cfq_pd_alloc,
.pd_init_fn = cfq_pd_init,
.pd_offline_fn = cfq_pd_offline,
.pd_free_fn = cfq_pd_free,
.pd_reset_stats_fn = cfq_pd_reset_stats,
};
#endif
static int __init cfq_init(void)
{
int ret;
#ifdef CONFIG_CFQ_GROUP_IOSCHED
ret = blkcg_policy_register(&blkcg_policy_cfq);
if (ret)
return ret;
#else
cfq_group_idle = 0;
#endif
ret = -ENOMEM;
cfq_pool = KMEM_CACHE(cfq_queue, 0);
if (!cfq_pool)
goto err_pol_unreg;
ret = elv_register(&iosched_cfq);
if (ret)
goto err_free_pool;
return 0;
err_free_pool:
kmem_cache_destroy(cfq_pool);
err_pol_unreg:
#ifdef CONFIG_CFQ_GROUP_IOSCHED
blkcg_policy_unregister(&blkcg_policy_cfq);
#endif
return ret;
}
static void __exit cfq_exit(void)
{
#ifdef CONFIG_CFQ_GROUP_IOSCHED
blkcg_policy_unregister(&blkcg_policy_cfq);
#endif
elv_unregister(&iosched_cfq);
kmem_cache_destroy(cfq_pool);
}
module_init(cfq_init);
module_exit(cfq_exit);
MODULE_AUTHOR("Jens Axboe");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
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