Messages in this thread | | | Date | Sat, 24 Apr 2021 10:30:00 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH v4] sched,fair: Skip newidle_balance if a wakeup is pending |
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On Thu, Apr 22, 2021 at 01:02:36PM -0400, Rik van Riel 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>
Acked-by: Mel Gorman <mgorman@suse.de>
-- Mel Gorman SUSE Labs
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