Re: [PATCH] x86/aperfmperf: Refresh stale sample via IPI for busy NOHZ_FULL CPUs

[Peter Zijlstra]

On Tue, Jul 28, 2026 at 07:27:54PM +0800, Jing Wu wrote:
> An isolated CPU covered by nohz_full stops its periodic tick once it
> has only one runnable task, since sched_can_stop_tick() only checks
> scheduling-class fairness and has no notion of cpufreq reporting
> needs. arch_scale_freq_tick() runs only from scheduler_tick(), so
> cpu_samples for that CPU is never refreshed again.

Sending IPIs to NOHZ_FULL Cpus should be a no-no.