Messages in this thread Patch in this message | | | From | Patrick Bellasi <> | Subject | [PATCH v2 1/6] cpufreq: schedutil: ignore sugov kthreads | Date | Tue, 4 Jul 2017 18:34:06 +0100 |
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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
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