Re: [Question]: try to fix contention between expire_timers and try_to_del_timer_sync

From: Vikram Mulukutla
Date: Thu Aug 03 2017 - 19:25:19 EST

Hi Will,

On 2017-07-31 06:13, Will Deacon wrote:
Hi Vikram,

On Fri, Jul 28, 2017 at 12:09:38PM -0700, Vikram Mulukutla wrote:
On 2017-07-28 02:28, Will Deacon wrote:
>On Thu, Jul 27, 2017 at 06:10:34PM -0700, Vikram Mulukutla wrote:

This does seem to help. Here's some data after 5 runs with and without the

Blimey, that does seem to make a difference. Shame it's so ugly! Would you
be able to experiment with other values for CPU_RELAX_WFE_THRESHOLD? I had
it set to 10000 in the diff I posted, but that might be higher than optimal.
It would be interested to see if it correlates with num_possible_cpus()
for the highly contended case.


Sorry for the late response - I should hopefully have some more data with
different thresholds before the week is finished or on Monday.

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