From: Andi Kleen <andi@firstfloor.org>
To: "Yan, Zheng" <zheng.z.yan@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org, mingo@kernel.org,
acme@infradead.org, eranian@google.com, andi@firstfloor.org
Subject: Re: [PATCH v3 6/9] perf, x86: handle multiple records in PEBS buffer
Date: Mon, 28 Jul 2014 05:36:29 +0200 [thread overview]
Message-ID: <20140728033629.GJ18735@two.firstfloor.org> (raw)
In-Reply-To: <53D5B45E.4030403@intel.com>
> I don't think this method works for interrupt threshold > 1 case. When collision
> happens, the hardware only create one PEBS record. The status in next record has
> nothing to do with the collision record.
>
Not even for the threshold == 1 case, because the same could happen with
a different PEBS event. Of course in any case it's very unlikely ...
>
> > So typically we'd have one event set and no problem, but in case there's
> > more we can reconstruct with such a backwards pass from a known good
> > state.
> >
> > But when in doubt, we should drop the record, its the safest choice.
>
> The problem is that, in some cases, each PEBS record has more than one events
> set, so we will drop all records.
Just dropping is fine imho, this should be rare.
-Andi
next prev parent reply other threads:[~2014-07-28 3:36 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-22 8:09 [PATCH v3 0/7] perf, x86: large PEBS interrupt threshold Yan, Zheng
2014-07-22 8:09 ` [PATCH v3 1/9] perf, core: introduce pmu context switch callback Yan, Zheng
2014-07-22 8:09 ` [PATCH v3 2/9] perf, x86: use context switch callback to flush LBR stack Yan, Zheng
2014-07-22 8:09 ` [PATCH v3 3/9] perf, x86: use the PEBS auto reload mechanism when possible Yan, Zheng
2014-07-22 8:09 ` [PATCH v3 4/9] perf, x86: introduce setup_pebs_sample_data() Yan, Zheng
2014-07-22 8:09 ` [PATCH v3 5/9] perf, x86: large PEBS interrupt threshold Yan, Zheng
2014-07-22 16:16 ` Andi Kleen
2014-07-23 0:59 ` Yan, Zheng
2014-07-22 8:09 ` [PATCH v3 6/9] perf, x86: handle multiple records in PEBS buffer Yan, Zheng
2014-07-25 8:10 ` Peter Zijlstra
2014-07-25 8:34 ` Yan, Zheng
2014-07-25 14:06 ` Peter Zijlstra
2014-07-28 2:24 ` Yan, Zheng
2014-07-28 3:36 ` Andi Kleen [this message]
2014-07-28 6:52 ` Peter Zijlstra
2014-07-31 7:31 ` Yan, Zheng
2014-07-31 14:44 ` Andi Kleen
2014-07-31 15:25 ` Peter Zijlstra
2014-07-25 15:04 ` Andi Kleen
2014-07-25 15:53 ` Peter Zijlstra
2014-07-25 16:40 ` Andi Kleen
2014-07-28 3:20 ` Yan, Zheng
2014-07-28 3:34 ` Andi Kleen
2014-07-28 6:54 ` Peter Zijlstra
2014-07-22 8:10 ` [PATCH v3 7/9] perf, x86: drain PEBS buffer during context switch Yan, Zheng
2014-07-22 8:10 ` [PATCH v3 8/9] perf, x86: enlarge PEBS buffer Yan, Zheng
2014-07-22 8:10 ` [PATCH v3 9/9] tools, perf: Allow the user to disable time stamps Yan, Zheng
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