Messages in this thread | | | Subject | Re: [PATCH] sched/cpufreq: Align trace event behavior of fast switching | From | Dietmar Eggemann <> | Date | Mon, 26 Aug 2019 11:51:17 +0200 |
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On 26/08/2019 11:40, Peter Zijlstra wrote: > On Mon, Aug 26, 2019 at 11:10:52AM +0200, Rafael J. Wysocki wrote: >> On Wednesday, August 7, 2019 5:33:40 PM CEST Douglas RAILLARD wrote: >>> Fast switching path only emits an event for the CPU of interest, whereas the >>> regular path emits an event for all the CPUs that had their frequency changed, >>> i.e. all the CPUs sharing the same policy. >>> >>> With the current behavior, looking at cpu_frequency event for a given CPU that >>> is using the fast switching path will not give the correct frequency signal. >>> >>> Signed-off-by: Douglas RAILLARD <douglas.raillard@arm.com> >>> --- >>> kernel/sched/cpufreq_schedutil.c | 7 ++++++- >>> 1 file changed, 6 insertions(+), 1 deletion(-) >>> >>> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c >>> index 1f82ab108bab..975ccc3de807 100644 >>> --- a/kernel/sched/cpufreq_schedutil.c >>> +++ b/kernel/sched/cpufreq_schedutil.c >>> @@ -153,6 +153,7 @@ static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time, >>> unsigned int next_freq) >>> { >>> struct cpufreq_policy *policy = sg_policy->policy; >>> + int cpu; >>> >>> if (!sugov_update_next_freq(sg_policy, time, next_freq)) >>> return; >>> @@ -162,7 +163,11 @@ static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time, >>> return; >>> >>> policy->cur = next_freq; >>> - trace_cpu_frequency(next_freq, smp_processor_id()); >>> + >>> + if (trace_cpu_frequency_enabled()) { >>> + for_each_cpu(cpu, policy->cpus) >>> + trace_cpu_frequency(next_freq, cpu); >>> + } >>> } >>> >>> static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time, >>> >> >> Peter, any comments here? > > I was thinking this would be a static map and dealing with it would be > something trivially done in post (or manually while reading), but sure, > whatever: > > Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
I think our EAS tooling expects the behavior of the non-fast-switching driver (cpufreq.c cpufreq_notify_transition() CPUFREQ_POSTCHANGE). Pixel 3 is the first device with a fast-switching driver we test on.
Not sure about the extra 'if trace_cpu_frequency_enabled()' but I guess it doesn't hurt.
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