linux-kernel - Re: [PATCH v3 0/3] perf: add option to limit callchain stack scan to increase speed

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Date:	Tue, 22 Oct 2013 15:12:22 -0400
From:	Waiman Long <waiman.long@...com>
To:	Namhyung Kim <namhyung@...nel.org>
CC:	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Jiri Olsa <jolsa@...hat.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	linux-kernel@...r.kernel.org,
	Aswin Chandramouleeswaran <aswin@...com>,
	Scott J Norton <scott.norton@...com>,
	Davidlohr Bueso <davidlohr@...com>
Subject: Re: [PATCH v3 0/3] perf: add option to limit callchain stack scan
 to increase speed

On 10/22/2013 02:07 PM, Namhyung Kim wrote:
> Hi Waiman,
>
> On Mon, 21 Oct 2013 11:03:36 -0400, Waiman Long wrote:
>> v2->v3:
>>   - Fix the commit log in the second patch which causes "git am" to fail.
>>   - Remove the 1st patch in v2 as the problem will be fixed by another
>>     patch from Arnaldo.
>>
>> v1->v2:
>>   - Include a compilation fix patch and a code streamlining patch
>>     into the patch set.
>>   - Use the __stringify() macro in stringify.h instead of adding a
>>     duplicate macro.
>>   - Add the --max-stack option to perf-top as well.
>>
>> This perf patch set contains the following changes:
>>
>> Patch 1 - Streamline the append_chain() function to make it run a bit
>>            faster.
>> Patch 2 - Add a --max-stack option to perf-report to speed up its
>>            processing at the expense of less backtrace information
>>            available.
>> Patch 3 - Add a similar --max-stack option to perf-top.
> At first, thank you for tackling this.  It was really a problem using
> callchain on non trivial perf session.  But there's another effort to
> address this problem in other direction.  You might want to see below
> link [1].  Patch 1/8 does the thing and it seems Arnaldo already merged
> it into his tree.

Thank for letting me aware of your patch to address the perf-report 
problem. As I am working on resolving scalability problem in large NUMA 
machines, I often encounters large perf.data files that took more than 
1/2 hour for perf-report to produce anything. It is kind of frustrating 
to wait so long. I like the performance improvement in your patch 1/8, 
coupled with the max-stack option, it can really speed thing up.

-Longman
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