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SubjectRE: [PATCH] perf_counter: Fix a race on perf_counter_ctx
>-----Original Message-----
>From: Ingo Molnar []
>Sent: Tuesday, August 18, 2009 4:00 PM
>To: Metzger, Markus T
>Cc: Peter Zijlstra;;;; linux-
>; Paul Mackerras
>Subject: Re: [PATCH] perf_counter: Fix a race on perf_counter_ctx
>* Metzger, Markus T <> wrote:
>> Well, that would push out the limit a bit, but it would still be
>> quite fragile.
>> Currently, I'm not sure that this (i.e. that the interrupt
>> handling takes too long) is the underlying problem of the hangs
>> that I'm seeing.
>I havent seen a plausible theory yet about why an actual lockup
>would happen on your box.

So you do not think that taking too long in the ISR could cause this?

And is it working on your box?

>Does the timer IRQ perhaps slow down to such a degree that it can
>never make progress and gets re-triggered again and again? We saw
>such things with the function tracer.

How would I test this?

>Did the sampling of kernel-mode tasks ever work with the old BTS

The old BTS code used circular buffers.


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