From: Peter Zijlstra <peterz@infradead.org>
To: Stephane Eranian <eranian@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
mingo@elte.hu, Robert Richter <robert.richter@amd.com>,
Vince Weaver <vweaver1@eecs.utk.edu>
Subject: Re: [BUG] perf_event: semantic of PERF_SAMPLE_READ unclear
Date: Fri, 26 Aug 2011 14:13:01 +0200 [thread overview]
Message-ID: <1314360781.11049.2.camel@twins> (raw)
In-Reply-To: <CABPqkBSaW3ShYbJoO6YdFpZ7Rt+OfszP8m-uLSoBjCWZYVQ0Bw@mail.gmail.com>
On Fri, 2011-08-26 at 14:02 +0200, Stephane Eranian wrote:
> On Thu, Aug 25, 2011 at 7:32 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Thu, 2011-08-25 at 19:19 +0200, Stephane Eranian wrote:
> >> But the difficulty is that
> >> we cannot grab any locks, not sure we need one given the call path.
> >
> > Nah we should be able to simply iterate all siblings and update them
> > in-place, since its group members they should all be co-scheduled. The
> > only difficulty is cross pmu group members..
> >
> Are we allowing event from different PMU to be in the same event group?
> If so, is that useful?
We allow software events, which can always be scheduled, to be part of a
hardware group. We don't allow mixing of different hardware pmus.
Allowing a software event is useful if for example the hardware pmu
doesn't have a sampling interrupt.
next prev parent reply other threads:[~2011-08-26 12:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-25 17:19 [BUG] perf_event: semantic of PERF_SAMPLE_READ unclear Stephane Eranian
2011-08-25 17:32 ` Peter Zijlstra
2011-08-25 21:24 ` Stephane Eranian
2011-08-26 12:02 ` Stephane Eranian
2011-08-26 12:08 ` Stephane Eranian
2011-08-26 12:13 ` Peter Zijlstra [this message]
2011-08-26 14:02 ` Stephane Eranian
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