Re: [PATCH] perf_events: fix read() bogus counts when in error state

[Stephane Eranian]

On Thu, Nov 26, 2009 at 6:36 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Thu, 2009-11-26 at 09:24 -0800, Stephane Eranian wrote:
>> Â Â Â When a pinned group cannot be scheduled it goes into error state.
>> Â Â Â Normally a group cannot go out of error state without being explicitly
>> Â Â Â re-enabled or disabled. There was a bug in per-thread mode, whereby
>> Â Â Â upon termination of the thread, the group would transition from error
>> Â Â Â to off leading to bogus counts and timing information returned by
>> Â Â Â read().
>
>> Â Â Â Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
>
> Right, good catch, totally forgot about error state :/
>
You need to clarify what pin actually means for per-thread
and I'd like to see an explanation for what happens when
sampling.
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