Messages in this thread Patch in this message | | | From | Patrick Bellasi <> | Subject | [PATCH 2/6] cpufreq: schedutil: ignore the sugov kthread for frequencies selections | Date | Thu, 2 Mar 2017 15:45:03 +0000 |
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In system where multiple CPUs shares the same frequency domain a small workload on a CPU can still be subject 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.
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 --- kernel/sched/cpufreq_schedutil.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 084a98b..a3fe5e4 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -274,6 +274,8 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, { struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util); struct sugov_policy *sg_policy = sg_cpu->sg_policy; + unsigned int cpu = smp_processor_id(); + struct task_struct *curr = cpu_curr(cpu); unsigned long util, max; unsigned int next_f; @@ -287,6 +289,10 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, goto done; } + /* Skip updates generated by sugov kthreads */ + if (curr == sg_policy->thread) + goto done; + sg_cpu->util = util; sg_cpu->max = max; sg_cpu->flags = flags; -- 2.7.4
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