From: Quentin Perret <qperret@google.com>
To: Douglas Raillard <douglas.raillard@arm.com>
Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net,
viresh.kumar@linaro.org, peterz@infradead.org,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com, linux-pm@vger.kernel.org
Subject: Re: [RFC PATCH v4 3/6] sched/cpufreq: Hook em_pd_get_higher_power() into get_next_freq()
Date: Fri, 24 Jan 2020 14:37:04 +0000 [thread overview]
Message-ID: <20200124143704.GA215244@google.com> (raw)
In-Reply-To: <5a2af4e7-f9eb-4f23-908a-fab2c7395a99@arm.com>
On Thursday 23 Jan 2020 at 17:52:53 (+0000), Douglas Raillard wrote:
> We can't really move the call to em_pd_get_higher_freq() into
> cpufreq_driver_resolve_freq() since that's a schedutil-specific feature,
> and we would loose the !sg_policy->need_freq_update optimization.
Depends how you do it. You could add a new method to cpufreq_policy that
is defined only for sugov or something along those lines. And you'd call
that instead of cpufreq_frequency_table_target() when that makes sense.
> Maybe we can add a flag to cpufreq_driver_resolve_freq() that promises
> that the frequency is already a valid one. We have to be careful though,
> since a number of things can make that untrue:
> - em_pd_get_higher_freq() will return the passed freq verbatim if it's
> higher than the max freq, so em_pd_get_higher_freq() will have to set
> the flag itself in case that logic changes.
> - policy limits can change the value
> - future things could tinker with the freq and forget to reset the flag.
>
> If you think it's worth it I can make these changes.
The thing is, not only with the current patch we end up iterating the
frequencies twice for nothing, but also I think it'd be interesting to
use the EM for consistency with EAS. It'd be nice to use the same data
structure for the predictions we do in compute_energy() and for the
actual request.
Thoughts ?
Quentin
next prev parent reply other threads:[~2020-01-24 14:37 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 [this message]
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
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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