workqueue: Avoid using isolated cpus' timers on queue_delayed_work

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When __queue_delayed_work() is called, it chooses a cpu for handling the
timer interrupt. As of today, it will pick either the cpu passed as
parameter or the last cpu used for this.

This is not good if a system does use CPU isolation, because it can take
away some valuable cpu time to:
1 - deal with the timer interrupt,
2 - schedule-out the desired task,
3 - queue work on a random workqueue, and
4 - schedule the desired task back to the cpu.

So to fix this, during __queue_delayed_work(), if cpu isolation is in
place, pick a random non-isolated cpu to handle the timer interrupt.

As an optimization, if the current cpu is not isolated, use it instead
of looking for another candidate.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

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Leonardo Bras 2024-01-29 22:00:46 -03:00 • committed by Tejun Heo

parent 07daa99b7f

commit aae17ebb53

1 changed files with 11 additions and 3 deletions

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kernel/workqueue.c

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