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x86/aperfmperf: Dont wake idle CPUs in arch_freq_get_on_cpu()

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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>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20220415161206.419880163@linutronix.de
This commit is contained in:
Thomas Gleixner 2022-04-15 21:19:50 +02:00
parent dbb5ab6d2c
commit 6d108c96bf
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kernel/cpu/aperfmperf.c
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@ -139,6 +139,9 @@ unsigned int arch_freq_get_on_cpu(int cpu)
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);