Re: [PATCH] sched/idle: disable tick in idle=poll idle entry

Peter Zijlstra
2023-06-08T08:34:13Z

On Wed, Jun 07, 2023 at 10:10:46PM -0300, Marcelo Tosatti wrote:
>
> Commit a5183862e76fdc25f36b39c2489b816a5c66e2e5
> ("tick/nohz: Conditionally restart tick on idle exit") allows
> a nohz_full CPU to enter idle and return from it with the
> scheduler tick disabled (since the tick might be undesired noise).
>
> The idle=poll case still unconditionally restarts the tick when entering
> idle.
>
> To reduce the noise for that case as well, stop the tick when entering
> idle, for the idle=poll case.
>
> tick_nohz_idle_exit (called if the NEED_RESCHED bit is set)
> is responsible for re-enabling the tick when necessary.

Who cares and why?