Re: contention on profile_lock
From: Jack Steiner
Date: Tue Nov 02 2004 - 15:19:48 EST
On Tue, Nov 02, 2004 at 11:52:15AM -0800, Jesse Barnes wrote:
> Hmm, the last patch you sent me worked ok, so I'm not sure why we're seeing
> problems with profiling now. There seems to be very heavy contention on
> profile_lock since profile_hook is called unconditionally every timer tick.
> Should it only be called if profiling is enabled? Is there a way we can
> check the notifier list to see if it's empty before calling it or something?
> The only user appears to be oprofile timer based profiling, so in the general
> case we're taking the profile_lock and not doing anything.
>
> Thanks,
> Jesse
Calling profile_hook() only if the notifier list is non-empty seems like a good
step but I don't think that is the complete fix. We need to be able to
enable profiling without killing performance.
--
Thanks
Jack Steiner (steiner@xxxxxxx) 651-683-5302
Principal Engineer SGI - Silicon Graphics, Inc.
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