| Date | Wed, 27 Apr 2022 13:56:14 -0000 | From | "tip-bot2 for Thomas Gleixner" <> | Subject | [tip: x86/cleanups] x86/aperfmperf: Dont wake idle CPUs in arch_freq_get_on_cpu() |
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The following commit has been merged into the x86/cleanups branch of tip:
Commit-ID: 6d108c96bf23598cc3b4f91d60e9b7694abcd2a7 Gitweb: https://git.kernel.org/tip/6d108c96bf23598cc3b4f91d60e9b7694abcd2a7 Author: Thomas Gleixner <tglx@linutronix.de> AuthorDate: Fri, 15 Apr 2022 21:19:50 +02:00 Committer: Thomas Gleixner <tglx@linutronix.de> CommitterDate: Wed, 27 Apr 2022 15:51:08 +02:00
x86/aperfmperf: Dont wake idle CPUs in arch_freq_get_on_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> 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
--- arch/x86/kernel/cpu/aperfmperf.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c index 9ca008f..ea9160f 100644 --- 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 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);
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