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authorJohannes Weiner <hannes@cmpxchg.org>2018-10-26 15:06:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-10-26 16:26:32 -0700
commitb1d29ba82cf2bc784f4c963ddd6a2cf29e229b33 (patch)
tree4fc15315a4c1f8c1d1e99968a3077dcf1ac45407
parent1899ad18c6072d689896badafb81267b0a1092a4 (diff)
downloadlinux-b1d29ba82cf2bc784f4c963ddd6a2cf29e229b33.tar.bz2
delayacct: track delays from thrashing cache pages
Delay accounting already measures the time a task spends in direct reclaim and waiting for swapin, but in low memory situations tasks spend can spend a significant amount of their time waiting on thrashing page cache. This isn't tracked right now. To know the full impact of memory contention on an individual task, measure the delay when waiting for a recently evicted active cache page to read back into memory. Also update tools/accounting/getdelays.c: [hannes@computer accounting]$ sudo ./getdelays -d -p 1 print delayacct stats ON PID 1 CPU count real total virtual total delay total delay average 50318 745000000 847346785 400533713 0.008ms IO count delay total delay average 435 122601218 0ms SWAP count delay total delay average 0 0 0ms RECLAIM count delay total delay average 0 0 0ms THRASHING count delay total delay average 19 12621439 0ms Link: http://lkml.kernel.org/r/20180828172258.3185-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Daniel Drake <drake@endlessm.com> Tested-by: Suren Baghdasaryan <surenb@google.com> Cc: Christopher Lameter <cl@linux.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <jweiner@fb.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Enderborg <peter.enderborg@sony.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vinayak Menon <vinmenon@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/delayacct.h23
-rw-r--r--include/uapi/linux/taskstats.h6
-rw-r--r--kernel/delayacct.c15
-rw-r--r--mm/filemap.c11
-rw-r--r--tools/accounting/getdelays.c8
5 files changed, 61 insertions, 2 deletions
diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
index 31c865d1842e..577d1b25fccd 100644
--- a/include/linux/delayacct.h
+++ b/include/linux/delayacct.h
@@ -57,7 +57,12 @@ struct task_delay_info {
u64 freepages_start;
u64 freepages_delay; /* wait for memory reclaim */
+
+ u64 thrashing_start;
+ u64 thrashing_delay; /* wait for thrashing page */
+
u32 freepages_count; /* total count of memory reclaim */
+ u32 thrashing_count; /* total count of thrash waits */
};
#endif
@@ -76,6 +81,8 @@ 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);
+extern void __delayacct_thrashing_start(void);
+extern void __delayacct_thrashing_end(void);
static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
{
@@ -156,6 +163,18 @@ static inline void delayacct_freepages_end(void)
__delayacct_freepages_end();
}
+static inline void delayacct_thrashing_start(void)
+{
+ if (current->delays)
+ __delayacct_thrashing_start();
+}
+
+static inline void delayacct_thrashing_end(void)
+{
+ if (current->delays)
+ __delayacct_thrashing_end();
+}
+
#else
static inline void delayacct_set_flag(int flag)
{}
@@ -182,6 +201,10 @@ static inline void delayacct_freepages_start(void)
{}
static inline void delayacct_freepages_end(void)
{}
+static inline void delayacct_thrashing_start(void)
+{}
+static inline void delayacct_thrashing_end(void)
+{}
#endif /* CONFIG_TASK_DELAY_ACCT */
diff --git a/include/uapi/linux/taskstats.h b/include/uapi/linux/taskstats.h
index b7aa7bb2349f..5e8ca16a9079 100644
--- a/include/uapi/linux/taskstats.h
+++ b/include/uapi/linux/taskstats.h
@@ -34,7 +34,7 @@
*/
-#define TASKSTATS_VERSION 8
+#define TASKSTATS_VERSION 9
#define TS_COMM_LEN 32 /* should be >= TASK_COMM_LEN
* in linux/sched.h */
@@ -164,6 +164,10 @@ struct taskstats {
/* Delay waiting for memory reclaim */
__u64 freepages_count;
__u64 freepages_delay_total;
+
+ /* Delay waiting for thrashing page */
+ __u64 thrashing_count;
+ __u64 thrashing_delay_total;
};
diff --git a/kernel/delayacct.c b/kernel/delayacct.c
index ca8ac2824f0b..2a12b988c717 100644
--- a/kernel/delayacct.c
+++ b/kernel/delayacct.c
@@ -135,9 +135,12 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
+ tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;
+ d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;
d->blkio_count += tsk->delays->blkio_count;
d->swapin_count += tsk->delays->swapin_count;
d->freepages_count += tsk->delays->freepages_count;
+ d->thrashing_count += tsk->delays->thrashing_count;
raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
return 0;
@@ -169,3 +172,15 @@ void __delayacct_freepages_end(void)
&current->delays->freepages_count);
}
+void __delayacct_thrashing_start(void)
+{
+ current->delays->thrashing_start = ktime_get_ns();
+}
+
+void __delayacct_thrashing_end(void)
+{
+ delayacct_end(&current->delays->lock,
+ &current->delays->thrashing_start,
+ &current->delays->thrashing_delay,
+ &current->delays->thrashing_count);
+}
diff --git a/mm/filemap.c b/mm/filemap.c
index 7997adce5a29..01a841f17bf4 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -36,6 +36,7 @@
#include <linux/cleancache.h>
#include <linux/shmem_fs.h>
#include <linux/rmap.h>
+#include <linux/delayacct.h>
#include "internal.h"
#define CREATE_TRACE_POINTS
@@ -1073,8 +1074,15 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
{
struct wait_page_queue wait_page;
wait_queue_entry_t *wait = &wait_page.wait;
+ bool thrashing = false;
int ret = 0;
+ if (bit_nr == PG_locked && !PageSwapBacked(page) &&
+ !PageUptodate(page) && PageWorkingset(page)) {
+ delayacct_thrashing_start();
+ thrashing = true;
+ }
+
init_wait(wait);
wait->flags = lock ? WQ_FLAG_EXCLUSIVE : 0;
wait->func = wake_page_function;
@@ -1113,6 +1121,9 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
finish_wait(q, wait);
+ if (thrashing)
+ delayacct_thrashing_end();
+
/*
* A signal could leave PageWaiters set. Clearing it here if
* !waitqueue_active would be possible (by open-coding finish_wait),
diff --git a/tools/accounting/getdelays.c b/tools/accounting/getdelays.c
index 9f420d98b5fb..8cb504d30384 100644
--- a/tools/accounting/getdelays.c
+++ b/tools/accounting/getdelays.c
@@ -203,6 +203,8 @@ static void print_delayacct(struct taskstats *t)
"SWAP %15s%15s%15s\n"
" %15llu%15llu%15llums\n"
"RECLAIM %12s%15s%15s\n"
+ " %15llu%15llu%15llums\n"
+ "THRASHING%12s%15s%15s\n"
" %15llu%15llu%15llums\n",
"count", "real total", "virtual total",
"delay total", "delay average",
@@ -222,7 +224,11 @@ static void print_delayacct(struct taskstats *t)
"count", "delay total", "delay average",
(unsigned long long)t->freepages_count,
(unsigned long long)t->freepages_delay_total,
- average_ms(t->freepages_delay_total, t->freepages_count));
+ average_ms(t->freepages_delay_total, t->freepages_count),
+ "count", "delay total", "delay average",
+ (unsigned long long)t->thrashing_count,
+ (unsigned long long)t->thrashing_delay_total,
+ average_ms(t->thrashing_delay_total, t->thrashing_count));
}
static void task_context_switch_counts(struct taskstats *t)