On Thu, 25 Apr 2013 11:09:56 +0200, Jiri Olsa wrote:
> On Thu, Apr 25, 2013 at 03:06:37PM +0900, Namhyung Kim wrote:
>> 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 <[email protected]>
>> >> +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.
>
> ugh, sry.. I wrote set_ftrace_pid when I actually meant tracing_cpumask ;-)
Okay. :)
>
>>
>> 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.
>
>
> looks like it's enough only to open it with O_TRUNC,
> so I guess whatever minimal goes write_tracing_file
Yeah, but I can see below from trace-cmd code.
trace-cmd/trace-record.c:
/*
* Older kernels required "-1" to disable pid
*/
if (ret < 0 && !strlen(pid))
ret = write(fd, "-1", 2);
Could you clarify this, Steve?
Thanks,
Namhyung
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