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Subject: Re: [BUG] perf_event: semantic of PERF_SAMPLE_READ unclear
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>
Date: Thu, 25 Aug 2011 19:32:40 +0200
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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..