Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Tue, 22 Jun 2021 14:28:11 +0200 | Subject | Re: [RFC PATCH 3/4] cpufreq: Add Active Stats calls tracking frequency changes |
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On Tue, Jun 22, 2021 at 9:59 AM Lukasz Luba <lukasz.luba@arm.com> wrote: > > The Active Stats framework tracks and accounts the activity of the CPU > for each performance level. It accounts the real residency, when the CPU > was not idle, at a given performance level. This patch adds needed calls > which provide the CPU frequency transition events to the Active Stats > framework. > > Signed-off-by: Lukasz Luba <lukasz.luba@arm.com> > --- > drivers/cpufreq/cpufreq.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 802abc925b2a..d79cb9310572 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -14,6 +14,7 @@ > > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > +#include <linux/active_stats.h> > #include <linux/cpu.h> > #include <linux/cpufreq.h> > #include <linux/cpu_cooling.h> > @@ -387,6 +388,8 @@ static void cpufreq_notify_transition(struct cpufreq_policy *policy, > > cpufreq_stats_record_transition(policy, freqs->new); > policy->cur = freqs->new; > + > + active_stats_cpu_freq_change(policy->cpu, freqs->new); > } > } > > @@ -2085,6 +2088,8 @@ unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy, > policy->cpuinfo.max_freq); > cpufreq_stats_record_transition(policy, freq); > > + active_stats_cpu_freq_fast_change(policy->cpu, freq); > +
This is quite a bit of overhead and so why is it needed in addition to the code below?
And pretty much the same goes for the idle loop change. There is quite a bit of instrumentation in that code already and it avoids adding new locking for a reason. Why is it a good idea to add more locking to that code?
> if (trace_cpu_frequency_enabled()) { > for_each_cpu(cpu, policy->cpus) > trace_cpu_frequency(freq, cpu); > --
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