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From: Peter Zijlstra <peterz@infradead.org>
To: Brendan Gregg <bgregg@netflix.com>
Cc: Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	linux-kernel@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
	Wang Nan <wangnan0@huawei.com>
Subject: Re: [PATCH v2 1/3] perf/core: Add a tracepoint for perf sampling
Date: Thu, 4 Aug 2016 16:28:53 +0200	[thread overview]
Message-ID: <20160804142853.GO6862@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CAJN39oiS1NiPsAZnvvOrO8rLC=k4nVofJ-AkyAQq9Y2PGvSsVw@mail.gmail.com>

On Wed, Aug 03, 2016 at 11:57:05AM -0700, Brendan Gregg wrote:

> As for pmu tracepoints: if I were to instrument it (although I wasn't
> planning to), I'd put a tracepoint in perf_event_overflow() called
> "perf:perf_overflow", with the same arguments. That could then be used
> for all PMU overflow events, without needing to add specific
> tracepoints. 

Could we not teach BPF to replace event->overflow_handler and inject
itself there?

We don't currently have nice interfaces for doing that, but it should be
possible to do I think. We already have the indirect function call, so
injecting ourself there has 0 overhead.

  reply	other threads:[~2016-08-04 14:29 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-03  2:47 [PATCH v2 0/3] Add a tracepoint for BPF " Brendan Gregg
2016-08-03  2:47 ` [PATCH v2 1/3] perf/core: Add a tracepoint for " Brendan Gregg
2016-08-03  9:48   ` Peter Zijlstra
2016-08-03 18:57     ` Brendan Gregg
2016-08-04 14:28       ` Peter Zijlstra [this message]
2016-08-05  1:43         ` Alexei Starovoitov
2016-08-05  4:13           ` Brendan Gregg
2016-08-05  5:24             ` Alexei Starovoitov
2016-08-05 10:52               ` Peter Zijlstra
2016-08-05 17:22                 ` Brendan Gregg
2016-08-08  9:57                   ` Peter Zijlstra
2016-08-05 19:45                 ` Alexei Starovoitov
2016-08-08 10:03                   ` Peter Zijlstra
2016-08-03  2:47 ` [PATCH v2 2/3] samples/bpf: Add a sampling BPF example Brendan Gregg
2016-08-03  2:47 ` [PATCH v2 3/3] perf script: add bpf-output field to usage message Brendan Gregg
2016-08-09 19:16   ` [tip:perf/urgent] perf script: Add 'bpf-output' " tip-bot for Brendan Gregg

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