From: Patrick Bellasi <patrick.bellasi@arm.com>
To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Juri Lelli <juri.lelli@arm.com>,
Joel Fernandes <joelaf@google.com>,
Andres Oportus <andresoportus@google.com>,
Todd Kjos <tkjos@android.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>
Subject: [PATCH v2 1/6] cpufreq: schedutil: ignore sugov kthreads
Date: Tue, 4 Jul 2017 18:34:06 +0100 [thread overview]
Message-ID: <1499189651-18797-2-git-send-email-patrick.bellasi@arm.com> (raw)
In-Reply-To: <1499189651-18797-1-git-send-email-patrick.bellasi@arm.com>
In system where multiple CPUs shares the same frequency domain a small
workload on a CPU can still be subject to frequency spikes, generated by
the activation of the sugov's kthread.
Since the sugov kthread is a special RT task, which goal is just that to
activate a frequency transition, it does not make sense for it to bias
the schedutil's frequency selection policy.
This patch exploits the information related to the current task to silently
ignore cpufreq_update_this_cpu() calls, coming from the RT scheduler, while
the sugov kthread is running.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
---
Changes from v1:
- move check before policy spinlock (JuriL)
---
kernel/sched/cpufreq_schedutil.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index c982dd0..eaba6d6 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -218,6 +218,10 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
unsigned int next_f;
bool busy;
+ /* Skip updates generated by sugov kthreads */
+ if (unlikely(current == sg_policy->thread))
+ return;
+
sugov_set_iowait_boost(sg_cpu, time, flags);
sg_cpu->last_update = time;
@@ -290,6 +294,10 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
unsigned long util, max;
unsigned int next_f;
+ /* Skip updates generated by sugov kthreads */
+ if (unlikely(current == sg_policy->thread))
+ return;
+
sugov_get_util(&util, &max);
raw_spin_lock(&sg_policy->update_lock);
--
2.7.4
next prev parent reply other threads:[~2017-07-04 17:34 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-04 17:34 [PATCH v2 0/6] cpufreq: schedutil: fixes for flags updates Patrick Bellasi
2017-07-04 17:34 ` Patrick Bellasi [this message]
2017-07-05 5:00 ` [PATCH v2 1/6] cpufreq: schedutil: ignore sugov kthreads Viresh Kumar
2017-07-05 11:38 ` Patrick Bellasi
2017-07-06 4:50 ` Viresh Kumar
2017-07-06 22:18 ` Rafael J. Wysocki
2017-07-11 19:08 ` Saravana Kannan
2017-07-04 17:34 ` [PATCH v2 2/6] cpufreq: schedutil: reset sg_cpus's flags at IDLE enter Patrick Bellasi
2017-07-05 4:50 ` Viresh Kumar
2017-07-05 13:04 ` Patrick Bellasi
2017-07-06 5:46 ` Viresh Kumar
2017-07-07 4:43 ` Joel Fernandes
2017-07-07 10:17 ` Juri Lelli
2017-07-11 19:16 ` Saravana Kannan
2017-07-04 17:34 ` [PATCH v2 3/6] cpufreq: schedutil: ensure max frequency while running RT/DL tasks Patrick Bellasi
2017-07-05 6:01 ` Viresh Kumar
2017-07-05 13:41 ` Patrick Bellasi
2017-07-06 5:56 ` Viresh Kumar
2017-07-07 5:26 ` Joel Fernandes
2017-07-04 17:34 ` [PATCH v2 4/6] cpufreq: schedutil: update CFS util only if used Patrick Bellasi
2017-07-07 5:58 ` Joel Fernandes
2017-07-07 6:44 ` Vikram Mulukutla
2017-07-08 6:14 ` Joel Fernandes
2017-07-10 17:49 ` Vikram Mulukutla
2017-07-11 5:19 ` Joel Fernandes
2017-07-04 17:34 ` [PATCH v2 5/6] sched/rt: fast switch to maximum frequency when RT tasks are scheduled Patrick Bellasi
2017-07-04 17:34 ` [PATCH v2 6/6] cpufreq: schedutil: relax rate-limiting while running RT/DL tasks Patrick Bellasi
2017-07-06 22:26 ` [PATCH v2 0/6] cpufreq: schedutil: fixes for flags updates Rafael J. Wysocki
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