linux-kernel - Re: [RFC 00/14] perf tools: Introduce new 'ftrace' command

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Date:	Wed, 24 Apr 2013 19:14:49 +0800
From:	"zhangwei(Jovi)" <jovi.zhangwei@...wei.com>
To:	Namhyung Kim <namhyung@...nel.org>
CC:	Steven Rostedt <rostedt@...dmis.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>, David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [RFC 00/14] perf tools: Introduce new 'ftrace' command

On 2013/4/24 17:27, Namhyung Kim wrote:
> Hi Steve,
> 
> On Tue, 23 Apr 2013 11:58:01 -0400, Steven Rostedt wrote:
>> On Tue, 2013-04-23 at 17:30 +0900, Namhyung Kim wrote:
>>> Hello,
>>>
>>> This patchset implements a front-end tool for kernel's ftrace.  It
>>> uses function_graph tracer by default and normal function tracer is
>>> also supported.  (Of course you need to enable those tracers in your
>>> kernel first.)
>>>
>>> NOTE: It's in very early stage, so may contain many rough edges.
>>>
>>
>> Very nice Namhyung, thanks for doing this. I did a quick run through of
>> the patches and I have no complaints about them. I'm not sure how the
>> others will feel about it.
> 
> Thanks!
> 
>>
>> Also, have you given thought on how to execute both ftrace and the pmu
>> counters? That is, to get a way to interleave the data?
> 
> I didn't think about it yet.  I just thought enabling event tracing in
> ftrace and get the data along with the function tracing.  I'm not sure
> how they interfere each other when enabled at the same time.
> 
> If that's not a valid concern, I think it's doable.

There have ftrace:function event in tracing infrastructure, that event works in perf,
but I'm not sure if it could enhance to showing function graph as this patchset did.
	perf record -e ftrace:function ls > /dev/null
	perf report

> 
> 
>> I added a 'perf' clock to ftrace. I didn't see that being checked,
>> although I didn't look too hard. If possible, you can use that, as well
>> as the multi-buffers that are coming in 3.10.
> 
> Will look at it later.
> 
>>
>> I would also like to add a system call to allow you to get to the ftrace
>> data without the need for debugfs. I'm not sure if we should piggy back
>> on the perf system call, or add a new one. I'm thinking we should add a
>> new one so that it doesn't get too confusing.
> 
> Could you elaborate on it more?  I cannot see how it'll look like..
> 
>>
>> Hope others have comments,
> 
> Thanks for your kind review.
> Namhyung
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