From: Peter Zijlstra <peterz@infradead.org>
To: eranian@gmail.com
Cc: Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: PEBS bug on HSW: "Unexpected number of pebs records 10" (was: Re: [GIT PULL] perf changes for v3.12)
Date: Tue, 10 Sep 2013 17:28:45 +0200 [thread overview]
Message-ID: <20130910152845.GI31370@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CAMsRxfJ5HG+0AiooOUFh8TzvCoK3YcBFpeAF0eTzdkDm=wB84g@mail.gmail.com>
On Tue, Sep 10, 2013 at 07:15:19AM -0700, Stephane Eranian wrote:
> The threshold is where to generate the interrupt. It does not mean
> where to stop PEBS recording.
It does, since we don't set a reset value. So once a PEBS assist
happens, that counter stops until we reprogram it in the PMI.
> So it is possible that in HSW, we may
> get into a situation where it takes time to get to the handler to stop
> the PMU. I don't know how given we use NMI. Well, unless we were
> already servicing an NMI at the time. But given that we stop the PMU
> almost immediately in the handler, I don't see how that would
> possible. The other oddity in HSW is that we clear the NMI on entry
> to the handler and not at the end. I never gotten an good explanation
> as to why that was necessary. So maybe it is related...
Even if the PMI was delayed that counter would never do another entry.
So I really don't see how we can have more than nr_counters PEBS entries
in the buffer.
next prev parent reply other threads:[~2013-09-10 15:29 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-03 13:29 [GIT PULL] perf changes for v3.12 Ingo Molnar
2013-09-03 13:37 ` Arnaldo Carvalho de Melo
2013-09-03 13:43 ` Ingo Molnar
2013-09-03 17:02 ` Vince Weaver
2013-09-04 17:53 ` Linus Torvalds
2013-09-05 10:56 ` Ingo Molnar
2013-09-05 12:42 ` Frederic Weisbecker
2013-09-05 12:51 ` Ingo Molnar
2013-09-05 12:58 ` Frederic Weisbecker
2013-09-10 8:06 ` Namhyung Kim
2013-09-10 11:18 ` Frederic Weisbecker
2013-09-05 13:38 ` Ingo Molnar
2013-09-08 2:17 ` Linus Torvalds
2013-09-09 10:05 ` Peter Zijlstra
2013-09-10 11:28 ` Stephane Eranian
2013-09-10 11:53 ` PEBS bug on HSW: "Unexpected number of pebs records 10" (was: Re: [GIT PULL] perf changes for v3.12) Ingo Molnar
2013-09-10 12:32 ` Stephane Eranian
2013-09-10 12:42 ` Ramkumar Ramachandra
2013-09-10 12:51 ` Ramkumar Ramachandra
2013-09-10 12:55 ` Stephane Eranian
2013-09-10 13:22 ` Ingo Molnar
2013-09-10 13:38 ` Ingo Molnar
2013-09-10 14:15 ` Stephane Eranian
2013-09-10 14:29 ` Ingo Molnar
2013-09-10 14:34 ` Stephane Eranian
2013-09-10 17:14 ` Ingo Molnar
2013-09-16 11:07 ` Stephane Eranian
2013-09-16 15:41 ` Ingo Molnar
2013-09-16 16:29 ` Peter Zijlstra
2013-09-17 7:00 ` Ingo Molnar
2013-09-23 15:25 ` Stephane Eranian
2013-09-23 15:33 ` Peter Zijlstra
2013-09-23 17:11 ` Stephane Eranian
2013-09-23 17:24 ` Peter Zijlstra
2013-09-10 15:28 ` Peter Zijlstra [this message]
2013-09-10 16:14 ` Stephane Eranian
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