From: Andi Kleen <andi@firstfloor.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Yan\, Zheng" <zheng.z.yan@intel.com>,
linux-kernel@vger.kernel.org, mingo@kernel.org,
acme@infradead.org, eranian@google.com
Subject: Re: [PATCH v4 0/9] perf, x86: large PEBS interrupt threshold
Date: Thu, 31 Jul 2014 07:50:44 -0700 [thread overview]
Message-ID: <8761idr397.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <20140731072744.GN19379@twins.programming.kicks-ass.net> (Peter Zijlstra's message of "Thu, 31 Jul 2014 09:27:44 +0200")
Peter Zijlstra <peterz@infradead.org> writes:
>
> No feedback on the correctness aspects of the overflow crap?
I assume you mean collisions? See below.
> A quick look at patch 6 reads like you still don't understand the issue
> right. There are no 'collisions' as such in PEBS record generation, or
> are there? See the earlier open discussion.
There can be collisions, but they are in practice extremely rare.
The only way you can get a lot of collision is if you count
the same thing multiple times which is not a useful configuration.
A single monitoring tool only needs a single event once.
While multiple processes may be configuring multiple events
at the same time, they will not start them at the same
time which also prevents collisions.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
prev parent reply other threads:[~2014-07-31 14:50 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-31 6:44 [PATCH v4 0/9] perf, x86: large PEBS interrupt threshold Yan, Zheng
2014-07-31 6:44 ` [PATCH v4 1/9] perf, core: introduce pmu context switch callback Yan, Zheng
2014-07-31 6:44 ` [PATCH v4 2/9] perf, x86: use context switch callback to flush LBR stack Yan, Zheng
2014-07-31 6:44 ` [PATCH v4 3/9] perf, x86: use the PEBS auto reload mechanism when possible Yan, Zheng
2014-07-31 6:44 ` [PATCH v4 4/9] perf, x86: introduce setup_pebs_sample_data() Yan, Zheng
2014-07-31 6:45 ` [PATCH v4 5/9] perf, x86: large PEBS interrupt threshold Yan, Zheng
2014-07-31 6:45 ` [PATCH v4 6/9] perf, x86: handle multiple records in PEBS buffer Yan, Zheng
2014-07-31 6:45 ` [PATCH v4 7/9] perf, x86: drain PEBS buffer during context switch Yan, Zheng
2014-07-31 6:45 ` [PATCH v4 8/9] perf, x86: enlarge PEBS buffer Yan, Zheng
2014-07-31 6:45 ` [PATCH v4 9/9] tools, perf: Allow the user to disable time stamps Yan, Zheng
2014-07-31 14:45 ` Arnaldo Carvalho de Melo
2014-08-13 5:13 ` [tip:perf/core] perf record: Honour --no-time command line option tip-bot for Andi Kleen
2014-07-31 7:16 ` [PATCH v4 0/9] perf, x86: large PEBS interrupt threshold Ingo Molnar
2014-07-31 7:18 ` Yan, Zheng
2014-07-31 7:25 ` Ingo Molnar
2014-07-31 7:27 ` Peter Zijlstra
2014-07-31 7:36 ` Yan, Zheng
2014-07-31 7:49 ` Peter Zijlstra
2014-07-31 14:50 ` Andi Kleen [this message]
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