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Date: Fri, 17 Jul 2015 19:45:02 +0800 From: "Wangnan (F)" <wangnan0@...wei.com> To: Peter Zijlstra <peterz@...radead.org> CC: kaixu xia <xiakaixu@...wei.com>, <ast@...mgrid.com>, <davem@...emloft.net>, <acme@...nel.org>, <mingo@...hat.com>, <masami.hiramatsu.pt@...achi.com>, <jolsa@...nel.org>, <linux-kernel@...r.kernel.org>, <pi3orama@....com>, <hekuang@...wei.com> Subject: Re: [RFC PATCH 5/6] bpf: Implement function bpf_read_pmu() that get the selected hardware PMU conuter On 2015/7/17 19:39, Peter Zijlstra wrote: > On Fri, Jul 17, 2015 at 07:29:07PM +0800, Wangnan (F) wrote: >> >> 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@...wei.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? > Depends on what all you need, if you need full perf events to work then > yes perf_event_read_value() is your only option. > > But note that that requires scheduling, so you cannot actually use it > for tracing purposes etc.. What you mean "full perf events"? Even with your code some event still not work? Thank you. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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