Messages in this thread | | | Date | Fri, 17 Jul 2015 19:29:07 +0800 | From | "Wangnan (F)" <> | Subject | Re: [RFC PATCH 5/6] bpf: Implement function bpf_read_pmu() that get the selected hardware PMU conuter |
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On 2015/7/17 19:05, Peter Zijlstra wrote: > On Fri, Jul 17, 2015 at 06:43:35PM +0800, kaixu xia wrote: >> The function bpf_read_pmu() can get the specific map key, convert >> the corresponding map value to the pointer to struct perf_event and >> return the Hardware PMU counter value. > Thanks for having me on Cc :/ > >> Signed-off-by: kaixu xia <xiakaixu@huawei.com> >> --- >> +static u64 bpf_read_pmu(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) >> +{ >> + void *value = (void *) (unsigned long) r1; >> + struct perf_event *event; >> + u64 count; >> + >> + if (!value || !(*(unsigned long *)value)) >> + return 0; >> + >> + event = (struct perf_event *)(*(unsigned long *)value); >> + >> + if (event->state == PERF_EVENT_STATE_ACTIVE) >> + event->pmu->read(event); >> + >> + count = local64_read(&event->count); >> + >> + return count; >> +} > Hell no, that's way broken. What about calling perf_event_read_value() then?
... struct perf_event_context *ctx; u64 enabled, u64 running
ctx = perf_event_ctx_lock(event); if (!event->state == PERF_EVENT_STATE_ERROR) { count = perf_event_read_value(event, &enable, &running); } perf_event_ctx_unlock(event, ctx); ...
Code is from perf_read().
Thank you.
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