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>
diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
index 31c865d..577d1b2 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 */