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Date: Tue, 3 Jun 2008 19:38:25 -0700
From: Keika Kobayashi <kobayashi.kk@...s.nec.co.jp>
To: linux-kernel@...r.kernel.org
Cc: akpm@...ux-foundation.org
Subject: [PATCH 1/4] 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 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@...s.nec.co.jp>
---
include/linux/delayacct.h | 19 +++++++++++++++++++
include/linux/sched.h | 4 ++++
kernel/delayacct.c | 13 +++++++++++++
mm/page_alloc.c | 3 +++
4 files changed, 39 insertions(+), 0 deletions(-)
diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
index ab94bc0..f352f06 100644
--- a/include/linux/delayacct.h
+++ b/include/linux/delayacct.h
@@ -39,6 +39,8 @@ 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)
{
@@ -107,6 +109,18 @@ static inline __u64 delayacct_blkio_ticks(struct task_struct *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)
{}
@@ -129,6 +143,11 @@ 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
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3e05e54..e6c557c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -666,6 +666,10 @@ struct task_delay_info {
/* io operations performed */
u32 swapin_count; /* total count of the number of swapin block */
/* io operations performed */
+
+ struct timespec freepages_start, freepages_end;
+ u64 freepages_delay; /* wait for memory reclaim */
+ u32 freepages_count; /* total count of memory reclaim */
};
#endif /* CONFIG_TASK_DELAY_ACCT */
diff --git a/kernel/delayacct.c b/kernel/delayacct.c
index 10e43fd..84b6782 100644
--- a/kernel/delayacct.c
+++ b/kernel/delayacct.c
@@ -165,3 +165,16 @@ __u64 __delayacct_blkio_ticks(struct task_struct *tsk)
return ret;
}
+void __delayacct_freepages_start(void)
+{
+ delayacct_start(¤t->delays->freepages_start);
+}
+
+void __delayacct_freepages_end(void)
+{
+ delayacct_end(¤t->delays->freepages_start,
+ ¤t->delays->freepages_end,
+ ¤t->delays->freepages_delay,
+ ¤t->delays->freepages_count);
+}
+
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8e83f02..8b4e606 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -46,6 +46,7 @@
#include <linux/page-isolation.h>
#include <linux/memcontrol.h>
#include <linux/debugobjects.h>
+#include <linux/delayacct.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -1571,7 +1572,9 @@ nofail_alloc:
reclaim_state.reclaimed_slab = 0;
p->reclaim_state = &reclaim_state;
+ delayacct_freepages_start();
did_some_progress = try_to_free_pages(zonelist, order, gfp_mask);
+ delayacct_freepages_end();
p->reclaim_state = NULL;
p->flags &= ~PF_MEMALLOC;
--
1.5.0.6
--
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