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linux-next/include/linux/memcontrol.h
Johannes Weiner 241994ed86 mm: memcontrol: default hierarchy interface for memory 
Introduce the basic control files to account, partition, and limit
memory using cgroups in default hierarchy mode.

This interface versioning allows us to address fundamental design
issues in the existing memory cgroup interface, further explained
below.  The old interface will be maintained indefinitely, but a
clearer model and improved workload performance should encourage
existing users to switch over to the new one eventually.

The control files are thus:

  - memory.current shows the current consumption of the cgroup and its
    descendants, in bytes.

  - memory.low configures the lower end of the cgroup's expected
    memory consumption range.  The kernel considers memory below that
    boundary to be a reserve - the minimum that the workload needs in
    order to make forward progress - and generally avoids reclaiming
    it, unless there is an imminent risk of entering an OOM situation.

  - memory.high configures the upper end of the cgroup's expected
    memory consumption range.  A cgroup whose consumption grows beyond
    this threshold is forced into direct reclaim, to work off the
    excess and to throttle new allocations heavily, but is generally
    allowed to continue and the OOM killer is not invoked.

  - memory.max configures the hard maximum amount of memory that the
    cgroup is allowed to consume before the OOM killer is invoked.

  - memory.events shows event counters that indicate how often the
    cgroup was reclaimed while below memory.low, how often it was
    forced to reclaim excess beyond memory.high, how often it hit
    memory.max, and how often it entered OOM due to memory.max.  This
    allows users to identify configuration problems when observing a
    degradation in workload performance.  An overcommitted system will
    have an increased rate of low boundary breaches, whereas increased
    rates of high limit breaches, maximum hits, or even OOM situations
    will indicate internally overcommitted cgroups.

For existing users of memory cgroups, the following deviations from
the current interface are worth pointing out and explaining:

  - The original lower boundary, the soft limit, is defined as a limit
    that is per default unset.  As a result, the set of cgroups that
    global reclaim prefers is opt-in, rather than opt-out.  The costs
    for optimizing these mostly negative lookups are so high that the
    implementation, despite its enormous size, does not even provide
    the basic desirable behavior.  First off, the soft limit has no
    hierarchical meaning.  All configured groups are organized in a
    global rbtree and treated like equal peers, regardless where they
    are located in the hierarchy.  This makes subtree delegation
    impossible.  Second, the soft limit reclaim pass is so aggressive
    that it not just introduces high allocation latencies into the
    system, but also impacts system performance due to overreclaim, to
    the point where the feature becomes self-defeating.

    The memory.low boundary on the other hand is a top-down allocated
    reserve.  A cgroup enjoys reclaim protection when it and all its
    ancestors are below their low boundaries, which makes delegation
    of subtrees possible.  Secondly, new cgroups have no reserve per
    default and in the common case most cgroups are eligible for the
    preferred reclaim pass.  This allows the new low boundary to be
    efficiently implemented with just a minor addition to the generic
    reclaim code, without the need for out-of-band data structures and
    reclaim passes.  Because the generic reclaim code considers all
    cgroups except for the ones running low in the preferred first
    reclaim pass, overreclaim of individual groups is eliminated as
    well, resulting in much better overall workload performance.

  - The original high boundary, the hard limit, is defined as a strict
    limit that can not budge, even if the OOM killer has to be called.
    But this generally goes against the goal of making the most out of
    the available memory.  The memory consumption of workloads varies
    during runtime, and that requires users to overcommit.  But doing
    that with a strict upper limit requires either a fairly accurate
    prediction of the working set size or adding slack to the limit.
    Since working set size estimation is hard and error prone, and
    getting it wrong results in OOM kills, most users tend to err on
    the side of a looser limit and end up wasting precious resources.

    The memory.high boundary on the other hand can be set much more
    conservatively.  When hit, it throttles allocations by forcing
    them into direct reclaim to work off the excess, but it never
    invokes the OOM killer.  As a result, a high boundary that is
    chosen too aggressively will not terminate the processes, but
    instead it will lead to gradual performance degradation.  The user
    can monitor this and make corrections until the minimal memory
    footprint that still gives acceptable performance is found.

    In extreme cases, with many concurrent allocations and a complete
    breakdown of reclaim progress within the group, the high boundary
    can be exceeded.  But even then it's mostly better to satisfy the
    allocation from the slack available in other groups or the rest of
    the system than killing the group.  Otherwise, memory.max is there
    to limit this type of spillover and ultimately contain buggy or
    even malicious applications.

  - The original control file names are unwieldy and inconsistent in
    many different ways.  For example, the upper boundary hit count is
    exported in the memory.failcnt file, but an OOM event count has to
    be manually counted by listening to memory.oom_control events, and
    lower boundary / soft limit events have to be counted by first
    setting a threshold for that value and then counting those events.
    Also, usage and limit files encode their units in the filename.
    That makes the filenames very long, even though this is not
    information that a user needs to be reminded of every time they
    type out those names.

    To address these naming issues, as well as to signal clearly that
    the new interface carries a new configuration model, the naming
    conventions in it necessarily differ from the old interface.

  - The original limit files indicate the state of an unset limit with
    a very high number, and a configured limit can be unset by echoing
    -1 into those files.  But that very high number is implementation
    and architecture dependent and not very descriptive.  And while -1
    can be understood as an underflow into the highest possible value,
    -2 or -10M etc. do not work, so it's not inconsistent.

    memory.low, memory.high, and memory.max will use the string
    "infinity" to indicate and set the highest possible value.

[akpm@linux-foundation.org: use seq_puts() for basic strings]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:02 -08:00

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/* memcontrol.h - Memory Controller
*
* Copyright IBM Corporation, 2007
* Author Balbir Singh <balbir@linux.vnet.ibm.com>
*
* Copyright 2007 OpenVZ SWsoft Inc
* Author: Pavel Emelianov <xemul@openvz.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#ifndef _LINUX_MEMCONTROL_H
#define _LINUX_MEMCONTROL_H
#include <linux/cgroup.h>
#include <linux/vm_event_item.h>
#include <linux/hardirq.h>
#include <linux/jump_label.h>
struct mem_cgroup;
struct page;
struct mm_struct;
struct kmem_cache;
/*
* The corresponding mem_cgroup_stat_names is defined in mm/memcontrol.c,
* These two lists should keep in accord with each other.
*/
enum mem_cgroup_stat_index {
/*
* For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
*/
MEM_CGROUP_STAT_CACHE, /* # of pages charged as cache */
MEM_CGROUP_STAT_RSS, /* # of pages charged as anon rss */
MEM_CGROUP_STAT_RSS_HUGE, /* # of pages charged as anon huge */
MEM_CGROUP_STAT_FILE_MAPPED, /* # of pages charged as file rss */
MEM_CGROUP_STAT_WRITEBACK, /* # of pages under writeback */
MEM_CGROUP_STAT_SWAP, /* # of pages, swapped out */
MEM_CGROUP_STAT_NSTATS,
};
struct mem_cgroup_reclaim_cookie {
struct zone *zone;
int priority;
unsigned int generation;
};
enum mem_cgroup_events_index {
MEM_CGROUP_EVENTS_PGPGIN, /* # of pages paged in */
MEM_CGROUP_EVENTS_PGPGOUT, /* # of pages paged out */
MEM_CGROUP_EVENTS_PGFAULT, /* # of page-faults */
MEM_CGROUP_EVENTS_PGMAJFAULT, /* # of major page-faults */
MEM_CGROUP_EVENTS_NSTATS,
/* default hierarchy events */
MEMCG_LOW = MEM_CGROUP_EVENTS_NSTATS,
MEMCG_HIGH,
MEMCG_MAX,
MEMCG_OOM,
MEMCG_NR_EVENTS,
};
#ifdef CONFIG_MEMCG
void mem_cgroup_events(struct mem_cgroup *memcg,
enum mem_cgroup_events_index idx,
unsigned int nr);
bool mem_cgroup_low(struct mem_cgroup *root, struct mem_cgroup *memcg);
int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask, struct mem_cgroup **memcgp);
void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
bool lrucare);
void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg);
void mem_cgroup_uncharge(struct page *page);
void mem_cgroup_uncharge_list(struct list_head *page_list);
void mem_cgroup_migrate(struct page *oldpage, struct page *newpage,
bool lrucare);
struct lruvec *mem_cgroup_zone_lruvec(struct zone *, struct mem_cgroup *);
struct lruvec *mem_cgroup_page_lruvec(struct page *, struct zone *);
bool mem_cgroup_is_descendant(struct mem_cgroup *memcg,
struct mem_cgroup *root);
bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg);
extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
extern struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg);
extern struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css);
static inline bool mm_match_cgroup(struct mm_struct *mm,
struct mem_cgroup *memcg)
{
struct mem_cgroup *task_memcg;
bool match = false;
rcu_read_lock();
task_memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (task_memcg)
match = mem_cgroup_is_descendant(task_memcg, memcg);
rcu_read_unlock();
return match;
}
extern struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg);
struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *,
struct mem_cgroup *,
struct mem_cgroup_reclaim_cookie *);
void mem_cgroup_iter_break(struct mem_cgroup *, struct mem_cgroup *);
/*
* For memory reclaim.
*/
int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec);
bool mem_cgroup_lruvec_online(struct lruvec *lruvec);
int mem_cgroup_select_victim_node(struct mem_cgroup *memcg);
unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list);
void mem_cgroup_update_lru_size(struct lruvec *, enum lru_list, int);
extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
struct task_struct *p);
static inline void mem_cgroup_oom_enable(void)
{
WARN_ON(current->memcg_oom.may_oom);
current->memcg_oom.may_oom = 1;
}
static inline void mem_cgroup_oom_disable(void)
{
WARN_ON(!current->memcg_oom.may_oom);
current->memcg_oom.may_oom = 0;
}
static inline bool task_in_memcg_oom(struct task_struct *p)
{
return p->memcg_oom.memcg;
}
bool mem_cgroup_oom_synchronize(bool wait);
#ifdef CONFIG_MEMCG_SWAP
extern int do_swap_account;
#endif
static inline bool mem_cgroup_disabled(void)
{
if (memory_cgrp_subsys.disabled)
return true;
return false;
}
struct mem_cgroup *mem_cgroup_begin_page_stat(struct page *page);
void mem_cgroup_update_page_stat(struct mem_cgroup *memcg,
enum mem_cgroup_stat_index idx, int val);
void mem_cgroup_end_page_stat(struct mem_cgroup *memcg);
static inline void mem_cgroup_inc_page_stat(struct mem_cgroup *memcg,
enum mem_cgroup_stat_index idx)
{
mem_cgroup_update_page_stat(memcg, idx, 1);
}
static inline void mem_cgroup_dec_page_stat(struct mem_cgroup *memcg,
enum mem_cgroup_stat_index idx)
{
mem_cgroup_update_page_stat(memcg, idx, -1);
}
unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
gfp_t gfp_mask,
unsigned long *total_scanned);
void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx);
static inline void mem_cgroup_count_vm_event(struct mm_struct *mm,
enum vm_event_item idx)
{
if (mem_cgroup_disabled())
return;
__mem_cgroup_count_vm_event(mm, idx);
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
void mem_cgroup_split_huge_fixup(struct page *head);
#endif
#else /* CONFIG_MEMCG */
struct mem_cgroup;
static inline void mem_cgroup_events(struct mem_cgroup *memcg,
enum mem_cgroup_events_index idx,
unsigned int nr)
{
}
static inline bool mem_cgroup_low(struct mem_cgroup *root,
struct mem_cgroup *memcg)
{
return false;
}
static inline int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask,
struct mem_cgroup **memcgp)
{
*memcgp = NULL;
return 0;
}
static inline void mem_cgroup_commit_charge(struct page *page,
struct mem_cgroup *memcg,
bool lrucare)
{
}
static inline void mem_cgroup_cancel_charge(struct page *page,
struct mem_cgroup *memcg)
{
}
static inline void mem_cgroup_uncharge(struct page *page)
{
}
static inline void mem_cgroup_uncharge_list(struct list_head *page_list)
{
}
static inline void mem_cgroup_migrate(struct page *oldpage,
struct page *newpage,
bool lrucare)
{
}
static inline struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
struct mem_cgroup *memcg)
{
return &zone->lruvec;
}
static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
struct zone *zone)
{
return &zone->lruvec;
}
static inline struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
{
return NULL;
}
static inline bool mm_match_cgroup(struct mm_struct *mm,
struct mem_cgroup *memcg)
{
return true;
}
static inline bool task_in_mem_cgroup(struct task_struct *task,
const struct mem_cgroup *memcg)
{
return true;
}
static inline struct cgroup_subsys_state
*mem_cgroup_css(struct mem_cgroup *memcg)
{
return NULL;
}
static inline struct mem_cgroup *
mem_cgroup_iter(struct mem_cgroup *root,
struct mem_cgroup *prev,
struct mem_cgroup_reclaim_cookie *reclaim)
{
return NULL;
}
static inline void mem_cgroup_iter_break(struct mem_cgroup *root,
struct mem_cgroup *prev)
{
}
static inline bool mem_cgroup_disabled(void)
{
return true;
}
static inline int
mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
{
return 1;
}
static inline bool mem_cgroup_lruvec_online(struct lruvec *lruvec)
{
return true;
}
static inline unsigned long
mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
{
return 0;
}
static inline void
mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
int increment)
{
}
static inline void
mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
{
}
static inline struct mem_cgroup *mem_cgroup_begin_page_stat(struct page *page)
{
return NULL;
}
static inline void mem_cgroup_end_page_stat(struct mem_cgroup *memcg)
{
}
static inline void mem_cgroup_oom_enable(void)
{
}
static inline void mem_cgroup_oom_disable(void)
{
}
static inline bool task_in_memcg_oom(struct task_struct *p)
{
return false;
}
static inline bool mem_cgroup_oom_synchronize(bool wait)
{
return false;
}
static inline void mem_cgroup_inc_page_stat(struct mem_cgroup *memcg,
enum mem_cgroup_stat_index idx)
{
}
static inline void mem_cgroup_dec_page_stat(struct mem_cgroup *memcg,
enum mem_cgroup_stat_index idx)
{
}
static inline
unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
gfp_t gfp_mask,
unsigned long *total_scanned)
{
return 0;
}
static inline void mem_cgroup_split_huge_fixup(struct page *head)
{
}
static inline
void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
{
}
#endif /* CONFIG_MEMCG */
enum {
UNDER_LIMIT,
SOFT_LIMIT,
OVER_LIMIT,
};
struct sock;
#if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
void sock_update_memcg(struct sock *sk);
void sock_release_memcg(struct sock *sk);
#else
static inline void sock_update_memcg(struct sock *sk)
{
}
static inline void sock_release_memcg(struct sock *sk)
{
}
#endif /* CONFIG_INET && CONFIG_MEMCG_KMEM */
#ifdef CONFIG_MEMCG_KMEM
extern struct static_key memcg_kmem_enabled_key;
extern int memcg_limited_groups_array_size;
/*
* Helper macro to loop through all memcg-specific caches. Callers must still
* check if the cache is valid (it is either valid or NULL).
* the slab_mutex must be held when looping through those caches
*/
#define for_each_memcg_cache_index(_idx) \
for ((_idx) = 0; (_idx) < memcg_limited_groups_array_size; (_idx)++)
static inline bool memcg_kmem_enabled(void)
{
return static_key_false(&memcg_kmem_enabled_key);
}
/*
* In general, we'll do everything in our power to not incur in any overhead
* for non-memcg users for the kmem functions. Not even a function call, if we
* can avoid it.
*
* Therefore, we'll inline all those functions so that in the best case, we'll
* see that kmemcg is off for everybody and proceed quickly. If it is on,
* we'll still do most of the flag checking inline. We check a lot of
* conditions, but because they are pretty simple, they are expected to be
* fast.
*/
bool __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **memcg,
int order);
void __memcg_kmem_commit_charge(struct page *page,
struct mem_cgroup *memcg, int order);
void __memcg_kmem_uncharge_pages(struct page *page, int order);
int memcg_cache_id(struct mem_cgroup *memcg);
void memcg_update_array_size(int num_groups);
struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep);
void __memcg_kmem_put_cache(struct kmem_cache *cachep);
int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp,
unsigned long nr_pages);
void memcg_uncharge_kmem(struct mem_cgroup *memcg, unsigned long nr_pages);
/**
* memcg_kmem_newpage_charge: verify if a new kmem allocation is allowed.
* @gfp: the gfp allocation flags.
* @memcg: a pointer to the memcg this was charged against.
* @order: allocation order.
*
* returns true if the memcg where the current task belongs can hold this
* allocation.
*
* We return true automatically if this allocation is not to be accounted to
* any memcg.
*/
static inline bool
memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **memcg, int order)
{
if (!memcg_kmem_enabled())
return true;
/*
* __GFP_NOFAIL allocations will move on even if charging is not
* possible. Therefore we don't even try, and have this allocation
* unaccounted. We could in theory charge it forcibly, but we hope
* those allocations are rare, and won't be worth the trouble.
*/
if (gfp & __GFP_NOFAIL)
return true;
if (in_interrupt() || (!current->mm) || (current->flags & PF_KTHREAD))
return true;
/* If the test is dying, just let it go. */
if (unlikely(fatal_signal_pending(current)))
return true;
return __memcg_kmem_newpage_charge(gfp, memcg, order);
}
/**
* memcg_kmem_uncharge_pages: uncharge pages from memcg
* @page: pointer to struct page being freed
* @order: allocation order.
*/
static inline void
memcg_kmem_uncharge_pages(struct page *page, int order)
{
if (memcg_kmem_enabled())
__memcg_kmem_uncharge_pages(page, order);
}
/**
* memcg_kmem_commit_charge: embeds correct memcg in a page
* @page: pointer to struct page recently allocated
* @memcg: the memcg structure we charged against
* @order: allocation order.
*
* Needs to be called after memcg_kmem_newpage_charge, regardless of success or
* failure of the allocation. if @page is NULL, this function will revert the
* charges. Otherwise, it will commit @page to @memcg.
*/
static inline void
memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg, int order)
{
if (memcg_kmem_enabled() && memcg)
__memcg_kmem_commit_charge(page, memcg, order);
}
/**
* memcg_kmem_get_cache: selects the correct per-memcg cache for allocation
* @cachep: the original global kmem cache
* @gfp: allocation flags.
*
* All memory allocated from a per-memcg cache is charged to the owner memcg.
*/
static __always_inline struct kmem_cache *
memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
{
if (!memcg_kmem_enabled())
return cachep;
if (gfp & __GFP_NOFAIL)
return cachep;
if (in_interrupt() || (!current->mm) || (current->flags & PF_KTHREAD))
return cachep;
if (unlikely(fatal_signal_pending(current)))
return cachep;
return __memcg_kmem_get_cache(cachep);
}
static __always_inline void memcg_kmem_put_cache(struct kmem_cache *cachep)
{
if (memcg_kmem_enabled())
__memcg_kmem_put_cache(cachep);
}
#else
#define for_each_memcg_cache_index(_idx) \
for (; NULL; )
static inline bool memcg_kmem_enabled(void)
{
return false;
}
static inline bool
memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **memcg, int order)
{
return true;
}
static inline void memcg_kmem_uncharge_pages(struct page *page, int order)
{
}
static inline void
memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg, int order)
{
}
static inline int memcg_cache_id(struct mem_cgroup *memcg)
{
return -1;
}
static inline struct kmem_cache *
memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
{
return cachep;
}
static inline void memcg_kmem_put_cache(struct kmem_cache *cachep)
{
}
#endif /* CONFIG_MEMCG_KMEM */
#endif /* _LINUX_MEMCONTROL_H */
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