kernel-ark/include/linux/delayacct.h
Keika Kobayashi 873b477177 per-task-delay-accounting: add memory reclaim delay
Sometimes, application responses become bad under heavy memory load.
Applications take a bit time to reclaim memory.  The statistics, how long
memory reclaim takes, will be useful to measure memory usage.

This patch adds accounting memory reclaim to per-task-delay-accounting for
accounting the time of do_try_to_free_pages().

<i.e>

- When System is under low memory load,
  memory reclaim may not occur.

$ free
             total       used       free     shared    buffers     cached
Mem:       8197800    1577300    6620500          0       4808    1516724
-/+ buffers/cache:      55768    8142032
Swap:     16386292          0   16386292

$ vmstat 1
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
 0  0      0 5069748  10612 3014060    0    0     0     0    3   26  0  0 100  0
 0  0      0 5069748  10612 3014060    0    0     0     0    4   22  0  0 100  0
 0  0      0 5069748  10612 3014060    0    0     0     0    3   18  0  0 100  0

Measure the time of tar command.

$ ls -s test.dat
1501472 test.dat

$ time tar cvf test.tar test.dat
real    0m13.388s
user    0m0.116s
sys     0m5.304s

$ ./delayget -d -p <pid>
CPU             count     real total  virtual total    delay total
                  428     5528345500     5477116080       62749891
IO              count    delay total
                  338     8078977189
SWAP            count    delay total
                    0              0
RECLAIM         count    delay total
                    0              0

- When system is under heavy memory load
  memory reclaim may occur.

$ vmstat 1
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
 0  0 7159032  49724   1812   3012    0    0     0     0    3   24  0  0 100  0
 0  0 7159032  49724   1812   3012    0    0     0     0    4   24  0  0 100  0
 0  0 7159032  49848   1812   3012    0    0     0     0    3   22  0  0 100  0

In this case, one process uses more 8G memory
by execution of malloc() and memset().

$ time tar cvf test.tar test.dat
real    1m38.563s        <-  increased by 85 sec
user    0m0.140s
sys     0m7.060s

$ ./delayget -d -p <pid>
CPU             count     real total  virtual total    delay total
                 9021     7140446250     7315277975      923201824
IO              count    delay total
                 8965    90466349669
SWAP            count    delay total
                    3       21036367
RECLAIM         count    delay total
                  740    61011951153

In the later case, the value of RECLAIM is increasing.
So, taskstats can show how much memory reclaim influences TAT.

Signed-off-by: Keika Kobayashi <kobayashi.kk@ncos.nec.co.jp>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujistu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 10:53:47 -07:00

154 lines
4.0 KiB
C

/* delayacct.h - per-task delay accounting
*
* Copyright (C) Shailabh Nagar, IBM Corp. 2006
*
* 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_DELAYACCT_H
#define _LINUX_DELAYACCT_H
#include <linux/sched.h>
#include <linux/taskstats_kern.h>
/*
* Per-task flags relevant to delay accounting
* maintained privately to avoid exhausting similar flags in sched.h:PF_*
* Used to set current->delays->flags
*/
#define DELAYACCT_PF_SWAPIN 0x00000001 /* I am doing a swapin */
#define DELAYACCT_PF_BLKIO 0x00000002 /* I am waiting on IO */
#ifdef CONFIG_TASK_DELAY_ACCT
extern int delayacct_on; /* Delay accounting turned on/off */
extern struct kmem_cache *delayacct_cache;
extern void delayacct_init(void);
extern void __delayacct_tsk_init(struct task_struct *);
extern void __delayacct_tsk_exit(struct task_struct *);
extern void __delayacct_blkio_start(void);
extern void __delayacct_blkio_end(void);
extern int __delayacct_add_tsk(struct taskstats *, struct task_struct *);
extern __u64 __delayacct_blkio_ticks(struct task_struct *);
extern void __delayacct_freepages_start(void);
extern void __delayacct_freepages_end(void);
static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
{
if (p->delays)
return (p->delays->flags & DELAYACCT_PF_BLKIO);
else
return 0;
}
static inline void delayacct_set_flag(int flag)
{
if (current->delays)
current->delays->flags |= flag;
}
static inline void delayacct_clear_flag(int flag)
{
if (current->delays)
current->delays->flags &= ~flag;
}
static inline void delayacct_tsk_init(struct task_struct *tsk)
{
/* reinitialize in case parent's non-null pointer was dup'ed*/
tsk->delays = NULL;
if (delayacct_on)
__delayacct_tsk_init(tsk);
}
/* Free tsk->delays. Called from bad fork and __put_task_struct
* where there's no risk of tsk->delays being accessed elsewhere
*/
static inline void delayacct_tsk_free(struct task_struct *tsk)
{
if (tsk->delays)
kmem_cache_free(delayacct_cache, tsk->delays);
tsk->delays = NULL;
}
static inline void delayacct_blkio_start(void)
{
delayacct_set_flag(DELAYACCT_PF_BLKIO);
if (current->delays)
__delayacct_blkio_start();
}
static inline void delayacct_blkio_end(void)
{
if (current->delays)
__delayacct_blkio_end();
delayacct_clear_flag(DELAYACCT_PF_BLKIO);
}
static inline int delayacct_add_tsk(struct taskstats *d,
struct task_struct *tsk)
{
if (!delayacct_on || !tsk->delays)
return 0;
return __delayacct_add_tsk(d, tsk);
}
static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
{
if (tsk->delays)
return __delayacct_blkio_ticks(tsk);
return 0;
}
static inline void delayacct_freepages_start(void)
{
if (current->delays)
__delayacct_freepages_start();
}
static inline void delayacct_freepages_end(void)
{
if (current->delays)
__delayacct_freepages_end();
}
#else
static inline void delayacct_set_flag(int flag)
{}
static inline void delayacct_clear_flag(int flag)
{}
static inline void delayacct_init(void)
{}
static inline void delayacct_tsk_init(struct task_struct *tsk)
{}
static inline void delayacct_tsk_free(struct task_struct *tsk)
{}
static inline void delayacct_blkio_start(void)
{}
static inline void delayacct_blkio_end(void)
{}
static inline int delayacct_add_tsk(struct taskstats *d,
struct task_struct *tsk)
{ return 0; }
static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
{ return 0; }
static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
{ return 0; }
static inline void delayacct_freepages_start(void)
{}
static inline void delayacct_freepages_end(void)
{}
#endif /* CONFIG_TASK_DELAY_ACCT */
#endif