Messages in this thread Patch in this message | | | From | Patrick Bellasi <> | Subject | [PATCH v3 6/6] cpufreq: schedutil: ignore sugov kthreads | Date | Thu, 30 Nov 2017 11:47:23 +0000 |
| |
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> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@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 v2: - rebased on v4.15-rc1 - moved at the end of the stack since considered more controversial Changes from v1: - move check before policy spinlock (JuriL)
Change-Id: I4d749458229b6496dd24a8c357be42cd35a739fd --- 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 3eea8884e61b..a93ad5b0c40d 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -270,6 +270,10 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, bool rt_mode; 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; @@ -356,6 +360,10 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int next_f; bool rt_mode; + /* Skip updates generated by sugov kthreads */ + if (unlikely(current == sg_policy->thread)) + return; + raw_spin_lock(&sg_policy->update_lock); sugov_get_util(&util, &max, sg_cpu->cpu); -- 2.14.1
| |