From: Peter Zijlstra <peterz@infradead.org>
To: "Wangnan (F)" <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>,
Kaixu Xia <xiakaixu@huawei.com>,
davem@davemloft.net, acme@kernel.org, mingo@redhat.com,
masami.hiramatsu.pt@hitachi.com, jolsa@kernel.org,
daniel@iogearbox.net, linux-kernel@vger.kernel.org,
pi3orama@163.com, hekuang@huawei.com, netdev@vger.kernel.org
Subject: Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling
Date: Wed, 21 Oct 2015 13:56:30 +0200 [thread overview]
Message-ID: <20151021115630.GO17308@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <56277844.9090201@huawei.com>
On Wed, Oct 21, 2015 at 07:34:28PM +0800, Wangnan (F) wrote:
> >If you want to actually disable the event: pmu->stop() will make it
> >stop, and you can restart using pmu->start().xiezuo
>
> I also prefer totally disabling event because our goal is to reduce
> sampling overhead as mush as possible. However, events in perf is
> CPU bounded, one event in perf cmdline becomes multiple 'perf_event'
> in kernel in multi-core system. Disabling/enabling events on all CPUs
> by a BPF program a hard task due to racing, NMI, ...
But eBPF perf events must already be local afaik. Look at the
constraints perf_event_read_local() places on the events.
next prev parent reply other threads:[~2015-10-21 11:56 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-20 7:22 [PATCH V5 0/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling Kaixu Xia
2015-10-20 7:22 ` [PATCH V5 1/1] " Kaixu Xia
2015-10-20 22:53 ` Alexei Starovoitov
2015-10-21 9:12 ` Peter Zijlstra
2015-10-21 10:31 ` xiakaixu
2015-10-21 11:33 ` Peter Zijlstra
2015-10-21 11:49 ` Wangnan (F)
2015-10-21 12:17 ` Peter Zijlstra
2015-10-21 13:42 ` Wangnan (F)
2015-10-21 13:49 ` Peter Zijlstra
2015-10-21 14:01 ` pi3orama
2015-10-21 14:09 ` Peter Zijlstra
2015-10-21 15:06 ` pi3orama
2015-10-21 16:57 ` Peter Zijlstra
2015-10-21 21:19 ` Alexei Starovoitov
2015-10-22 9:06 ` Peter Zijlstra
2015-10-22 10:28 ` Wangnan (F)
2015-10-23 12:52 ` Peter Zijlstra
2015-10-23 15:12 ` Peter Zijlstra
2015-10-27 6:43 ` xiakaixu
2015-10-22 2:46 ` Wangnan (F)
2015-10-22 7:39 ` Ingo Molnar
2015-10-22 7:51 ` Wangnan (F)
2015-10-22 9:24 ` Peter Zijlstra
2015-10-22 1:56 ` Wangnan (F)
2015-10-22 3:09 ` Alexei Starovoitov
2015-10-22 3:12 ` Wangnan (F)
2015-10-22 3:26 ` Alexei Starovoitov
2015-10-22 9:49 ` Peter Zijlstra
2015-10-21 11:34 ` Wangnan (F)
2015-10-21 11:56 ` Peter Zijlstra [this message]
2015-10-21 12:03 ` Wangnan (F)
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