Re: [PATCH 01/17] perf util: Save pid-cmdline mapping into tracingheader

[Namhyung Kim]

Hi Arnaldo,

2013-07-30 ìí 10:28, Arnaldo Carvalho de Melo ì ê:
> Em Tue, Jul 30, 2013 at 06:18:58PM +0900, Namhyung Kim escreveu:
> > From: Namhyung Kim <namhyung.kim@xxxxxxx>
> >
> > Current trace info data lacks the saved cmdline mapping which is
> > needed for pevent to find out the comm of a task.  Add this and bump
> > up the version number so that perf can determine its presence when
> > reading.
>
> Can't we get this from the PERF_RECORD_COMM synthesized at the beginning
> of the session + the kernel generated ones for new threads?
>
> We would just call machine__find_thread() and use thread->comm, etc, no?

Yes, I think it's doable.  However it needs an additional perf event 
only to generate the COMM events.  So I decided not to do it and reused 
saved cmdline info from ftrace.  But IIUC it also has a problem of 
possible information loss due to the size of table.

Thanks,
Namhyung

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