linux-kernel - Re: [PATCH 05/14] perf tools: Introduce new 'ftrace' tool

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Message-ID: <87fvyf9maa.fsf@sejong.aot.lge.com>
Date:	Thu, 25 Apr 2013 15:06:37 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	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>,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 05/14] perf tools: Introduce new 'ftrace' tool

On Wed, 24 Apr 2013 16:09:18 +0200, Jiri Olsa wrote:
> On Tue, Apr 23, 2013 at 05:31:03PM +0900, Namhyung Kim wrote:
>> From: Namhyung Kim <namhyung.kim@....com>
>> +out:
>> +	put_tracing_file(file);
>> +	return ret;
>> +}
>> +
>> +static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
>> +{
>> +	if (write_tracing_file("tracing_on", "0") < 0)
>> +		return -1;
>> +
>> +	if (write_tracing_file("current_tracer", "nop") < 0)
>> +		return -1;
>> +
>> +	if (write_tracing_file("set_ftrace_pid", " ") < 0)
>> +		return -1;
>
> I think we want to reset set_ftrace_pid file as well
> probably to -1..
>
> if I'm tracing command with this file having wrong CPU(s)
> I dont get any data..

Not sure I understood what you mean exactly.

Do you mean it should be changed to

	if (write_tracing_file("set_ftrace_pid", "-1") < 0)

?  It seems it's the right thing to do for compatibility.

Thanks,
Namhyung
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