Re: [RFC] [PATCH] Performance of del_single_shot_timer_sync

[Andrew Morton]

shobhit dayal <shobhit@xxxxxxxxxxxxxx> wrote:
>
> 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).
> 

And what is the overall improvement from the del_timer_sync speedup patch? 
I mean: overall runtime and CPU time improvements for a
relatively-real-world benchmark?
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