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SubjectRe: [PATCH v4 2/4] perf stat: add event unit and scale support
On Tue, Nov 5, 2013 at 3:00 PM, Jiri Olsa <> wrote:
> On Tue, Nov 05, 2013 at 02:34:45PM +0100, Stephane Eranian wrote:
>> Hi,
>> One thing I realized while testing is that we cannot simply add the
>> unit printout like that.
>> This may break all the scripts people may have written to parse the
>> output of perf stat.
> isn't it what the -x output is meant for?
> perf stat -x, ...
Somewhat. It is used to make parsing easy for the perf stat output.
But if you have a script that was expecting 2222267,cycles and now
is getting 222267,?,cycles. Things will break.

> 1.738605,task-clock
> 367,context-switches
> 0,cpu-migrations
> 272,page-faults
> 6722006,cycles
> 2592661,stalled-cycles-frontend
> 1935855,stalled-cycles-backend
> 4324013,instructions
> 823229,branches
> 11192,branch-misses
>> I think we need to make the display of the unit optional. If I do:
>> $ perf stat -e cycles ls
>> The output should remain as it was before and not show:
>> $ perf stat -e cycles ls
>> 22782847475 ? cycles
> maybe we should display just space ' ' instead
> of the '?' ...seems confusing
But then, it is not so good for the -x option to get ' ' in the csv output.

>> So I think we need a --show-unit option. It would be off by default.
>> Of course doing this causes a mess with the current code because
>> of all the various printf() in builtin-stat.c but I think it is better for
>> the end user.
>> Any opinion?
> I haven't checked by I think we changed the default perf stat
> output in the past without any fuzz
> maybe just keep the -x output or add the unit
> to the end of the line
Well, that's what I had initially. But then people thought it was more
natural to have in before the event. I agreed with that.

I almost have the --show-unit option working now. I think we should
go with that.

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