From: Douglas Raillard <douglas.raillard@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net,
viresh.kumar@linaro.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
qperret@google.com, linux-pm@vger.kernel.org
Subject: Re: [RFC PATCH v4 4/6] sched/cpufreq: Introduce sugov_cpu_ramp_boost
Date: Thu, 13 Feb 2020 10:49:09 +0000 [thread overview]
Message-ID: <56c3a7c0-0d41-809d-6929-086d7a9251b9@arm.com> (raw)
In-Reply-To: <20200210130802.GG14879@hirez.programming.kicks-ass.net>
On 2/10/20 1:08 PM, Peter Zijlstra wrote:
> On Wed, Jan 22, 2020 at 05:35:36PM +0000, Douglas RAILLARD wrote:
>
>> +static unsigned long sugov_cpu_ramp_boost_update(struct sugov_cpu *sg_cpu)
>> +{
>> + struct rq *rq = cpu_rq(sg_cpu->cpu);
>> + unsigned long util_est_enqueued;
>> + unsigned long util_avg;
>> + unsigned long boost = 0;
>> +
>
> Should we NO-OP this function when !sched_feat(UTIL_EST) ?
>
>> + util_est_enqueued = READ_ONCE(rq->cfs.avg.util_est.enqueued);
>
> Otherwise you're reading garbage here, no?
Most likely indeed. The boosting should be disabled in that case.
>
>> + util_avg = READ_ONCE(rq->cfs.avg.util_avg);
>> +
>> + /*
>> + * Boost when util_avg becomes higher than the previous stable
>> + * knowledge of the enqueued tasks' set util, which is CPU's
>> + * util_est_enqueued.
>> + *
>> + * We try to spot changes in the workload itself, so we want to
>> + * avoid the noise of tasks being enqueued/dequeued. To do that,
>> + * we only trigger boosting when the "amount of work" enqueued
>> + * is stable.
>> + */
>> + if (util_est_enqueued == sg_cpu->util_est_enqueued &&
>> + util_avg >= sg_cpu->util_avg &&
>> + util_avg > util_est_enqueued)
>> + boost = util_avg - util_est_enqueued;
>> +
>> + sg_cpu->util_est_enqueued = util_est_enqueued;
>> + sg_cpu->util_avg = util_avg;
>> + WRITE_ONCE(sg_cpu->ramp_boost, boost);
>> + return boost;
>> +}
next prev parent reply other threads:[~2020-02-13 10:49 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-22 17:35 [RFC PATCH v4 0/6] sched/cpufreq: Make schedutil energy aware Douglas RAILLARD
2020-01-22 17:35 ` [RFC PATCH v4 1/6] PM: Introduce em_pd_get_higher_freq() Douglas RAILLARD
2020-01-22 17:35 ` [RFC PATCH v4 2/6] sched/cpufreq: Attach perf domain to sugov policy Douglas RAILLARD
2020-01-22 17:35 ` [RFC PATCH v4 3/6] sched/cpufreq: Hook em_pd_get_higher_power() into get_next_freq() Douglas RAILLARD
2020-01-23 16:16 ` Quentin Perret
2020-01-23 17:52 ` Douglas Raillard
2020-01-24 14:37 ` Quentin Perret
2020-01-24 14:58 ` Quentin Perret
2020-02-27 15:51 ` Douglas Raillard
2020-01-22 17:35 ` [RFC PATCH v4 4/6] sched/cpufreq: Introduce sugov_cpu_ramp_boost Douglas RAILLARD
2020-01-23 15:55 ` Rafael J. Wysocki
2020-01-23 17:21 ` Douglas Raillard
2020-01-23 21:02 ` Rafael J. Wysocki
2020-01-28 15:38 ` Douglas Raillard
2020-02-10 13:08 ` Peter Zijlstra
2020-02-13 10:49 ` Douglas Raillard [this message]
2020-01-22 17:35 ` [RFC PATCH v4 5/6] sched/cpufreq: Boost schedutil frequency ramp up Douglas RAILLARD
2020-01-22 17:35 ` [RFC PATCH v4 6/6] sched/cpufreq: Add schedutil_em_tp tracepoint Douglas RAILLARD
2020-01-22 18:14 ` [RFC PATCH v4 0/6] sched/cpufreq: Make schedutil energy aware Douglas Raillard
2020-02-10 13:21 ` Peter Zijlstra
2020-02-13 17:49 ` Douglas Raillard
2020-02-14 12:21 ` Peter Zijlstra
2020-02-14 12:52 ` Peter Zijlstra
2020-03-11 12:25 ` Douglas Raillard
2020-02-14 13:37 ` Peter Zijlstra
2020-03-11 12:40 ` Douglas Raillard
2020-01-23 15:43 ` Rafael J. Wysocki
2020-01-23 17:16 ` Douglas Raillard
2020-02-10 13:30 ` Peter Zijlstra
2020-02-13 11:55 ` Douglas Raillard
2020-02-13 13:20 ` Peter Zijlstra
2020-02-27 15:50 ` Douglas Raillard
2020-01-27 17:16 ` Vincent Guittot
2020-02-10 11:37 ` Douglas Raillard
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