linux-kernel - Re: [PATCH 0/5] perf events finer grained context instrumentation / context exclusion

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Date:	Thu, 10 Jun 2010 08:26:18 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	Stephane Eranian <eranian@...gle.com>,
	Cyrill Gorcunov <gorcunov@...il.com>,
	Zhang Yanmin <yanmin_zhang@...ux.intel.com>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH 0/5] perf events finer grained context instrumentation /
 context exclusion


* Frederic Weisbecker <fweisbec@...il.com> wrote:

> Here is the new version of per context exclusion, based on hooks on 
> irq_enter/irq_exit. I haven't observed slowdowns but I haven't actually 
> measured the impact.

One thing that would be nice to see in this discussion is a comparison of 
before/after perf stat --repeat runs.

Something like:

  perf stat --repeat ./hackbench 5

Done with full stat, and then also done with hardirqs/softirqs excluded. (i.e. 
task context stats only)

I.e. does the feature really give us the expected statistical stability in 
results? Does it really exclude hardirq/softirq workloads, etc.?

Thanks,

	Ingo
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