Messages in this thread | | | Subject | Re: [PATCH 1/2] perf: Add munmap callback | From | "Liang, Kan" <> | Date | Wed, 24 Oct 2018 14:12:54 -0400 |
| |
On 10/24/2018 12:32 PM, Arnaldo Carvalho de Melo wrote: > Em Wed, Oct 24, 2018 at 09:23:34AM -0700, Andi Kleen escreveu: >>> +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. > > Right, look at how its counterpart, perf_event_mmap() works: > > void perf_event_mmap(struct vm_area_struct *vma) > { > struct perf_mmap_event mmap_event; > > if (!atomic_read(&nr_mmap_events)) > return; > <SNIP> > } >
Thanks. I'll add the nr_mmap_events check in V2.
Thanks, Kan
| |