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linux-next/include/linux/iocontext.h
Konstantin Khlebnikov bca4b914b5 cfq-iosched: remove dead_key from cfq_io_context
Remove ->dead_key field from cfq_io_context to shrink its size to 128 bytes.
(64 bytes for 32-bit hosts)

Use lower bit in ->key as dead-mark, instead of moving key to separate field.
After this for dead cfq_io_context we got cic->key != cfqd automatically.
Thus, io_context's last-hit cache should work without changing.

Now to check ->key for non-dead state compare it with cfqd,
instead of checking ->key for non-null value as it was before.

Plus remove obsolete race protection in cfq_cic_lookup.
This race gone after v2.6.24-1728-g4ac845a

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-05-24 09:06:59 +02:00

93 lines
2.0 KiB
C

#ifndef IOCONTEXT_H
#define IOCONTEXT_H
#include <linux/radix-tree.h>
#include <linux/rcupdate.h>
struct cfq_queue;
struct cfq_io_context {
void *key;
struct cfq_queue *cfqq[2];
struct io_context *ioc;
unsigned long last_end_request;
unsigned long ttime_total;
unsigned long ttime_samples;
unsigned long ttime_mean;
struct list_head queue_list;
struct hlist_node cic_list;
void (*dtor)(struct io_context *); /* destructor */
void (*exit)(struct io_context *); /* called on task exit */
struct rcu_head rcu_head;
};
/*
* I/O subsystem state of the associated processes. It is refcounted
* and kmalloc'ed. These could be shared between processes.
*/
struct io_context {
atomic_long_t refcount;
atomic_t nr_tasks;
/* all the fields below are protected by this lock */
spinlock_t lock;
unsigned short ioprio;
unsigned short ioprio_changed;
#if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
unsigned short cgroup_changed;
#endif
/*
* For request batching
*/
int nr_batch_requests; /* Number of requests left in the batch */
unsigned long last_waited; /* Time last woken after wait for request */
struct radix_tree_root radix_root;
struct hlist_head cic_list;
void *ioc_data;
};
static inline struct io_context *ioc_task_link(struct io_context *ioc)
{
/*
* if ref count is zero, don't allow sharing (ioc is going away, it's
* a race).
*/
if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
atomic_inc(&ioc->nr_tasks);
return ioc;
}
return NULL;
}
struct task_struct;
#ifdef CONFIG_BLOCK
int put_io_context(struct io_context *ioc);
void exit_io_context(struct task_struct *task);
struct io_context *get_io_context(gfp_t gfp_flags, int node);
struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
void copy_io_context(struct io_context **pdst, struct io_context **psrc);
#else
static inline void exit_io_context(struct task_struct *task)
{
}
struct io_context;
static inline int put_io_context(struct io_context *ioc)
{
return 1;
}
#endif
#endif