| Message ID | 20220415161206.419880163@linutronix.de |
|---|---|
| State | New |
| Headers | show |
| Series | x86/cpu: Consolidate APERF/MPERF code | expand |
On Fri, Apr 15, 2022 at 9:19 PM Thomas Gleixner <tglx@linutronix.de> wrote: > > aperfmperf_get_khz() already excludes idle CPUs from APERF/MPERF sampling > and that's a reasonable decision. There is no point in sending up to two > IPIs to an idle CPU just because someone reads a sysfs file. > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > arch/x86/kernel/cpu/aperfmperf.c | 3 +++ > 1 file changed, 3 insertions(+) > > --- a/arch/x86/kernel/cpu/aperfmperf.c > +++ b/arch/x86/kernel/cpu/aperfmperf.c > @@ -139,6 +139,9 @@ unsigned int arch_freq_get_on_cpu(int cp > if (!housekeeping_cpu(cpu, HK_TYPE_MISC)) > return 0; > > + if (rcu_is_idle_cpu(cpu)) > + return 0; > + > if (aperfmperf_snapshot_cpu(cpu, ktime_get(), true)) > return per_cpu(samples.khz, cpu); > >
--- a/arch/x86/kernel/cpu/aperfmperf.c +++ b/arch/x86/kernel/cpu/aperfmperf.c @@ -139,6 +139,9 @@ unsigned int arch_freq_get_on_cpu(int cp if (!housekeeping_cpu(cpu, HK_TYPE_MISC)) return 0; + if (rcu_is_idle_cpu(cpu)) + return 0; + if (aperfmperf_snapshot_cpu(cpu, ktime_get(), true)) return per_cpu(samples.khz, cpu);
aperfmperf_get_khz() already excludes idle CPUs from APERF/MPERF sampling and that's a reasonable decision. There is no point in sending up to two IPIs to an idle CPU just because someone reads a sysfs file. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/kernel/cpu/aperfmperf.c | 3 +++ 1 file changed, 3 insertions(+)