Re: [RFC] [PATCH] Performance of del_single_shot_timer_sync

[shobhit dayal <shobhit@calsoftinc.com>]

Andrew Morton wrote:
> By how much?  (CPU load, overall runtime, etc)
> 
> It's a bit odd to have an expired-timer-intensive workload.  Presumably
> postgres has some short-lived nanosleep or select-based polling loop in
> there which isn't doing much.

I am running this load on a numa hardware so I profile the kernel by logging
functions that cause remote node memory access. I generate a final log
that shows functions that cause remote memory accesses greater that 0.5%
of all remote memory access on the system.

del_timer_sync was responsible for about 2% of all remote memory
accesses on the system and came up as part of the top 10 functions who
were doing this. On top was schedule(7.52%) followed by
default_wake_function(2.79%). Rest every one in the top 10 were
around the range of 2%.

After the patch it never came up in the logs again( so less than 0.5% of
all faulting eip's).


regards
shobhit


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