Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Wed, 26 Jul 2023 17:07:27 +0200 | Subject | Re: Stopping the tick on a fully loaded system |
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On Wed, Jul 26, 2023 at 12:59 PM Frederic Weisbecker <frederic@kernel.org> wrote: > > Le Tue, Jul 25, 2023 at 04:27:56PM +0200, Rafael J. Wysocki a écrit : > > On Tue, Jul 25, 2023 at 3:07 PM Anna-Maria Behnsen > > I'll let Frederic respond to the above, but from my perspective it all > > just means that the idle governors in use today are not perfect. > > > > However, they will never be perfect, because they only have a little > > time to make a decision, so it's a matter of balancing that with > > precision. > > So, even without considering Anna-Maria's patchset, sparing > the next timer lookup if we already know we won't stop it would show > quite a benefit because that lookup involves locking and quite some > overhead walking through all levels.
You are right.
In principle, this can be done by using TICK_NSEC as the initial estimation of the idle duration and only calling tick_nohz_get_sleep_length() if the candidate state ends up in the higher bins. Interesting.
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