Re: [PATCH 1/2] perf: Add munmap callback

[Andi Kleen <ak@linux.intel.com>]

> +void perf_event_munmap(void)
> +{
> +	struct perf_cpu_context *cpuctx;
> +	unsigned long flags;
> +	struct pmu *pmu;
> +
> +	local_irq_save(flags);
> +	list_for_each_entry(cpuctx, this_cpu_ptr(&sched_cb_list), sched_cb_entry) {

Would be good have a fast path here that checks for the list being empty
without disabling the interrupts. munmap can be somewhat hot. I think
it's ok to make it slower with perf running, but we shouldn't impact
it without perf.

-Andi