linux-kernel - Re: [RFT][PATCH v2 0/3] cpuidle: teo: Do not check timers unconditionally every time

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Date:   Mon, 7 Aug 2023 17:38:34 +0200 (CEST)
From:   Anna-Maria Behnsen <anna-maria@...utronix.de>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
cc:     Linux PM <linux-pm@...r.kernel.org>,
        Kajetan Puchalski <kajetan.puchalski@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Frederic Weisbecker <frederic@...nel.org>
Subject: Re: [RFT][PATCH v2 0/3] cpuidle: teo: Do not check timers unconditionally
 every time

On Thu, 3 Aug 2023, Rafael J. Wysocki wrote:

> On Thu, Aug 3, 2023 at 11:12 PM Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> >
> > Hi Folks,
> >
> > This is the second iteration of:
> >
> > https://lore.kernel.org/linux-pm/4511619.LvFx2qVVIh@kreacher/
> >
> > with an additional patch.
> >
> > There are some small modifications of patch [1/3] and the new
> > patch causes governor statistics to play a role in deciding whether
> > or not to stop the scheduler tick.
> >
> > Testing would be much appreciated!
> 
> For convenience, this series is now available in the following git branch:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
>  pm-cpuidle-teo
> 

Gauthams tests and the distribution of idle time durations looks pretty
good. Also the prevention of calling tick_nohz_get_sleep_length() is very
nice (21477 calls of tick_nohz_next_event() and the tick was stopped 2670
times).

Here is the deviation of idle time durations (based on your branch):

Idle Total		2670	100.00%
x >= 4ms		2537	95.02%
4ms> x >= 2ms		19	0.71%
2ms > x >= 1ms		10	0.37%
1ms > x >= 500us	7	0.26%
500us > x >= 250us	6	0.22%
250us > x >=100us	13	0.49%
100us > x >= 50us	17	0.64%
50us > x >= 25us	25	0.94%
25us > x >= 10us	22	0.82%
10us > x > 5us		9	0.34%
5us > x			5	0.19%


Thanks,

	Anna-Maria