From: Viresh Kumar <viresh.kumar@linaro.org>
To: Lukasz Luba <lukasz.luba@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
peterz@infradead.org, rjw@rjwysocki.net,
vincent.guittot@linaro.org, qperret@google.com,
dietmar.eggemann@arm.com, vincent.donnefort@arm.com,
Beata.Michalska@arm.com, mingo@redhat.com, juri.lelli@redhat.com,
rostedt@goodmis.org, segall@google.com, mgorman@suse.de,
bristot@redhat.com, thara.gopinath@linaro.org,
amit.kachhap@gmail.com, amitk@kernel.org, rui.zhang@intel.com,
daniel.lezcano@linaro.org
Subject: Re: [PATCH v3 1/3] thermal: cpufreq_cooling: Update also offline CPUs per-cpu thermal_pressure
Date: Mon, 14 Jun 2021 15:42:13 +0530 [thread overview]
Message-ID: <20210614101213.enhmoyupag5d556r@vireshk-i7> (raw)
In-Reply-To: <20210610150324.22919-2-lukasz.luba@arm.com>
On 10-06-21, 16:03, Lukasz Luba wrote:
> The thermal pressure signal gives information to the scheduler about
> reduced CPU capacity due to thermal. It is based on a value stored in a
> per-cpu 'thermal_pressure' variable. The online CPUs will get the new
> value there, while the offline won't. Unfortunately, when the CPU is back
> online, the value read from per-cpu variable might be wrong (stale data).
> This might affect the scheduler decisions, since it sees the CPU capacity
> differently than what is actually available.
>
> Fix it by making sure that all online+offline CPUs would get the proper
> value in their per-cpu variable when thermal framework sets capping.
>
> Fixes: f12e4f66ab6a3 ("thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping")
> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
> ---
> drivers/thermal/cpufreq_cooling.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/cpufreq_cooling.c b/drivers/thermal/cpufreq_cooling.c
> index eeb4e4b76c0b..43b1ae8a7789 100644
> --- a/drivers/thermal/cpufreq_cooling.c
> +++ b/drivers/thermal/cpufreq_cooling.c
> @@ -478,7 +478,7 @@ static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
> ret = freq_qos_update_request(&cpufreq_cdev->qos_req, frequency);
> if (ret >= 0) {
> cpufreq_cdev->cpufreq_state = state;
> - cpus = cpufreq_cdev->policy->cpus;
> + cpus = cpufreq_cdev->policy->related_cpus;
> max_capacity = arch_scale_cpu_capacity(cpumask_first(cpus));
> capacity = frequency * max_capacity;
> capacity /= cpufreq_cdev->policy->cpuinfo.max_freq;
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
--
viresh
next prev parent reply other threads:[~2021-06-14 10:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 15:03 [PATCH v3 0/3] Add allowed CPU capacity knowledge to EAS Lukasz Luba
2021-06-10 15:03 ` [PATCH v3 1/3] thermal: cpufreq_cooling: Update also offline CPUs per-cpu thermal_pressure Lukasz Luba
2021-06-14 10:12 ` Viresh Kumar [this message]
2021-06-14 10:21 ` Lukasz Luba
2021-06-10 15:03 ` [PATCH v3 2/3] sched/fair: Take thermal pressure into account while estimating energy Lukasz Luba
2021-06-14 15:29 ` Lukasz Luba
2021-06-14 15:48 ` Vincent Guittot
2021-06-14 16:03 ` Vincent Guittot
2021-06-14 18:22 ` Lukasz Luba
2021-06-10 15:03 ` [PATCH v3 3/3] sched/cpufreq: Consider reduced CPU capacity in energy calculation Lukasz Luba
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