Messages in this thread | | | Subject | Re: [PATCH v3] sched,fair: skip newidle_balance if a wakeup is pending | From | Rik van Riel <> | Date | Thu, 22 Apr 2021 12:47:01 -0400 |
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On Thu, 2021-04-22 at 10:37 +0200, Vincent Guittot wrote: > On Wed, 21 Apr 2021 at 19:27, Vincent Guittot > <vincent.guittot@linaro.org> wrote: > > > > > - if (pulled_task) > > > + /* > > > + * If we are no longer idle, do not let the time spent > > > here pull > > > + * down this_rq->avg_idle. That could lead to > > > newidle_balance not > > > + * doing enough work, and the CPU actually going idle. > > > + */ > > > + if (pulled_task || this_rq->ttwu_pending) > > > I confirmed that the line above generate hackbench regression on my > large arm64 system (2 * 112 CPUs) > I'm testing hackbench with various number of group : 1, 2, 4, 16, 32, > 64, 128, 256 but I have only put the 2 results which significantly > regress. The other ones are in the +/-1% variation range > > hackbench -g $group > > group v5.12-rc8+tip w/ this patch w/ this patch > without > the line above > 64 2.862(+/- 9%) 2.952(+/-11%) -3% 2.807(+/- 7%) +2% > 128 3.334(+/-10%) 3.561-+/-13%) -7% 3.181(+/- 6%) +4%
OK, I guess this part of the patch needs additional work.
I'll send a v4 with just the first two changes.
Thank you for running those tests.
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