Messages in this thread | | | Date | Tue, 4 May 2021 11:21:44 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v4] sched,fair: Skip newidle_balance if a wakeup is pending |
| |
On Thu, Apr 22, 2021 at 07:09:46PM +0200, Vincent Guittot wrote: > On Thu, 22 Apr 2021 at 19:02, Rik van Riel <riel@surriel.com> wrote: > > > > The try_to_wake_up function has an optimization where it can queue > > a task for wakeup on its previous CPU, if the task is still in the > > middle of going to sleep inside schedule(). > > > > Once schedule() re-enables IRQs, the task will be woken up with an > > IPI, and placed back on the runqueue. > > > > If we have such a wakeup pending, there is no need to search other > > CPUs for runnable tasks. Just skip (or bail out early from) newidle > > balancing, and run the just woken up task. > > > > For a memcache like workload test, this reduces total CPU use by > > about 2%, proportionally split between user and system time, > > and p99 and p95 application response time by 10% on average. > > The schedstats run_delay number shows a similar improvement. > > > > Signed-off-by: Rik van Riel <riel@surriel.com> > > Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Thanks!
| |