From: "Wangnan (F)" <wangnan0@huawei.com>
To: Brendan Gregg <bgregg@netflix.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: <linux-kernel@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>
Subject: Re: [PATCH] perf/core: Add a tracepoint for perf sampling
Date: Sat, 30 Jul 2016 11:34:49 +0800 [thread overview]
Message-ID: <579C2059.9@huawei.com> (raw)
In-Reply-To: <CAJN39oibpBU9rZpAX2KJp2bNDj-gdrOMU+4xG14iuab5aPG-xg@mail.gmail.com>
On 2016/7/30 2:05, Brendan Gregg wrote:
> On Tue, Jul 19, 2016 at 4:20 PM, Brendan Gregg <bgregg@netflix.com> wrote:
>> When perf is performing hrtimer-based sampling, this tracepoint can be used
>> by BPF to run additional logic on each sample. For example, BPF can fetch
>> stack traces and frequency count them in kernel context, for an efficient
>> profiler.
> Any comments on this patch? Thanks,
>
> Brendan
Sorry for the late.
I think it is a useful feature. Could you please provide an example
to show how to use it in perf?
If I understand correctly, I can have a BPF script run 99 times per
second using
# perf -e cpu-clock/freq=99/ -e mybpf.c ...
And in mybpf.c, attach a BPF script on the new tracepoint. Right?
Also, since we already have timer:hrtimer_expire_entry, please provide
some further information about why we need a new tracepoint.
Thank you.
next prev parent reply other threads:[~2016-07-30 3:42 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-19 23:20 [PATCH] perf/core: Add a tracepoint for perf sampling Brendan Gregg
2016-07-29 18:05 ` Brendan Gregg
2016-07-30 3:34 ` Wangnan (F) [this message]
2016-08-03 2:44 ` Brendan Gregg
2016-07-29 19:21 ` Arnaldo Carvalho de Melo
2016-07-29 19:55 ` Brendan Gregg
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