From: Quentin Perret <quentin.perret@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
mingo@kernel.org, linux-kernel@vger.kernel.org,
rjw@rjwysocki.net, juri.lelli@redhat.com,
dietmar.eggemann@arm.com, Morten.Rasmussen@arm.com,
viresh.kumar@linaro.org, valentin.schneider@arm.com,
patrick.bellasi@arm.com, joel@joelfernandes.org,
daniel.lezcano@linaro.org, Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH v6 04/11] cpufreq/schedutil: use rt utilization tracking
Date: Fri, 22 Jun 2018 13:54:34 +0100 [thread overview]
Message-ID: <20180622125433.GA26461@e108498-lin.cambridge.arm.com> (raw)
In-Reply-To: <20180622113713.GJ2494@hirez.programming.kicks-ass.net>
On Friday 22 Jun 2018 at 13:37:13 (+0200), Peter Zijlstra wrote:
> That is true.. So we could limit the scaling to the case where there is
> no idle time, something like:
>
> util = sg_cpu->util_cfs;
>
> cap_cfs = (1024 - (sg_cpu->util_rt + ...));
> if (util == cap_cfs)
> util = sg_cpu->max;
>
> That specifically handles the '0% idle -> 100% freq' case, but I don't
> realy like edge behaviour like that. If for some reason it all doesn't
> quite align you're left with bits.
>
> And the linear scaling is the next simplest thing that avoids the hard
> boundary case.
Right, so maybe we'll get something smoother by just summing the signals
as Vincent is proposing ? You will still request max freq for the
(util == cap_cfs) case you described. By definition, you will have
(util_cfs + util_rt + ...) == 1024 in this case.
cap_cfs is the delta between RT+DL+... and 1024, and the only case where
util_cfs can be equal to cap_cfs is if util_cfs fills that delta
entirely.
I hope that makes sense
Thanks,
Quentin
next prev parent reply other threads:[~2018-06-22 12:54 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-08 12:09 [PATCH v6 00/11] track CPU utilization Vincent Guittot
2018-06-08 12:09 ` [PATCH v6 01/11] sched/pelt: Move pelt related code in a dedicated file Vincent Guittot
2018-06-08 12:09 ` [PATCH v6 02/11] sched/pelt: remove blank line Vincent Guittot
2018-06-21 14:33 ` Peter Zijlstra
2018-06-21 18:42 ` Vincent Guittot
2018-06-08 12:09 ` [PATCH v6 03/11] sched/rt: add rt_rq utilization tracking Vincent Guittot
2018-06-15 11:52 ` Dietmar Eggemann
2018-06-15 12:18 ` Vincent Guittot
2018-06-15 14:55 ` Dietmar Eggemann
2018-06-21 18:50 ` Peter Zijlstra
2018-06-08 12:09 ` [PATCH v6 04/11] cpufreq/schedutil: use rt " Vincent Guittot
2018-06-18 9:00 ` Dietmar Eggemann
2018-06-18 12:58 ` Vincent Guittot
2018-06-21 18:45 ` Peter Zijlstra
2018-06-21 18:57 ` Peter Zijlstra
2018-06-22 8:10 ` Vincent Guittot
2018-06-22 11:41 ` Peter Zijlstra
2018-06-22 12:14 ` Vincent Guittot
2018-06-22 7:58 ` Juri Lelli
2018-06-22 7:58 ` Quentin Perret
2018-06-22 11:37 ` Peter Zijlstra
2018-06-22 11:44 ` Peter Zijlstra
2018-06-22 12:23 ` Vincent Guittot
2018-06-22 13:26 ` Peter Zijlstra
2018-06-22 13:52 ` Peter Zijlstra
2018-06-22 13:54 ` Vincent Guittot
2018-06-22 13:57 ` Vincent Guittot
2018-06-22 14:46 ` Peter Zijlstra
2018-06-22 14:49 ` Vincent Guittot
2018-06-22 14:11 ` Peter Zijlstra
2018-06-22 14:48 ` Peter Zijlstra
2018-06-22 14:12 ` Vincent Guittot
2018-06-22 12:54 ` Quentin Perret [this message]
2018-06-22 13:29 ` Peter Zijlstra
2018-06-22 15:22 ` Peter Zijlstra
2018-06-22 15:30 ` Quentin Perret
2018-06-22 17:24 ` Vincent Guittot
2018-06-08 12:09 ` [PATCH v6 05/11] sched/dl: add dl_rq " Vincent Guittot
2018-06-08 12:09 ` [PATCH v6 06/11] cpufreq/schedutil: use dl " Vincent Guittot
2018-06-08 12:39 ` Juri Lelli
2018-06-08 12:48 ` Vincent Guittot
2018-06-08 12:54 ` Juri Lelli
2018-06-08 13:36 ` Juri Lelli
2018-06-08 13:38 ` Vincent Guittot
2018-06-22 15:24 ` Peter Zijlstra
2018-06-22 17:22 ` Vincent Guittot
2018-06-08 12:09 ` [PATCH v6 07/11] sched/irq: add irq " Vincent Guittot
2018-06-08 12:09 ` [PATCH v6 08/11] cpufreq/schedutil: take into account interrupt Vincent Guittot
2018-06-12 8:54 ` Dietmar Eggemann
2018-06-12 9:10 ` Vincent Guittot
2018-06-12 9:16 ` Vincent Guittot
2018-06-12 9:20 ` Quentin Perret
2018-06-12 9:26 ` Vincent Guittot
2018-06-08 12:09 ` [PATCH v6 09/11] sched: use pelt for scale_rt_capacity() Vincent Guittot
2018-06-08 12:09 ` [PATCH v6 10/11] sched: remove rt_avg code Vincent Guittot
2018-06-08 12:09 ` [PATCH v6 11/11] proc/sched: remove unused sched_time_avg_ms Vincent Guittot
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