Re: Re: [PATCH 2/2] trace-cmd: Support trace_clock extraction

From: Yoshihiro YUNOMAE
Date: Thu Apr 11 2013 - 06:09:11 EST

Hi Steven,

Thank you for reviewing my patch set.

(2013/04/10 1:00), Steven Rostedt wrote:
On Fri, 2013-04-05 at 10:54 +0900, Yoshihiro YUNOMAE wrote:
In this patch, trace-cmd reads trace_clock on debugfs in the report/extract
modes and outputs the data to trace.dat file. Then, in the report mode,
trace-cmd reads trace_clock data from the file and switches outputting format
of timestamp for each trace_clock.

Note that by applying this patch, the binary format of is changed
as follows:

<Current binary format>
[size of saved_cmdlines]
[saved_cmdlines contents]
[total cpu number]

<Changed binary format>
[size of saved_cmdlines]
[saved_cmdlines contents]
[size of trace_clock] <== add
[trace_clock contents] <== add
[total cpu number]

Hi Yoshihiro,

I don't mind the feature addition, but I don't like the implementation.
This will break backward compatibility with the trace.dat file, which
I've been working hard not to have happen.

Yeah, I agree with you.
It is important that trace-cmd keeps backward compatibility.

That doesn't mean that you can't implement this feature. This is what
the options section is for. You can add an option that includes the
trace_clock contents, or just simply say what type of clock is being
used. Then a new trace-cmd can show the output like you want it to, and
the old version will still work but show the old way, as trace-cmd is
made to simply ignore options it does not know about.

Sounds good.
Maintenance of the implementation will be easier than that of my

I think it's time for me to push my latest updates to trace-cmd. As this
will probably end up being the 3.0 version. I have examples there that
use the options feature for more extensions that you can look at.

Thank you for pushing your latest patches!
I'll use your patches as a reference and submit the revised patches
using the options feature.

Yoshihiro YUNOMAE

Yoshihiro YUNOMAE
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: yoshihiro.yunomae.ez@xxxxxxxxxxx

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at