Re: perf event attrributes

[Namhyung Kim <namhyung@kernel.org>]

Hi Chris,

On Mon, 1 Apr 2013 16:09:50 +0000, Freehill Christopher-RAT wrote:
> Andi,
>
> Thanks for the response.
>
> I am not familiar with "config/config1", but I infer from your message that I would make folders in sysfs for different event groups (?) and then have a file for each event that is a bit field that can be parsed. 
>
> As an alternative, is there anything to prevent encoding the attributes in the event ID itself? I think there are 64 bits to use. Some of those could be interpreted in a way specific to the event. I can see advantages and disadvantage to both. 
>
> Both ways seem a little convoluted from a user point of view. Seems
> like a more intuitive way would have been from the command line; ie,
> provide a way to pass info from the command line that could be
> interpreted in a way specific to the event. I'm sure that was probably
> considered, and there is a good reason that method wasn't chosen, but
> I do wonder...
>
> Can you point me to the Intel uncore drivers you mentioned?

You can see it under /sys/bus/event_source/devices/uncore_imc_*/ on a
recent kernel.  There'll be the "format" and "events" directories.

If you want to see the source, please go to:

  http://lxr.linux.no/#linux+v3.8.5/arch/x86/kernel/cpu/perf_event_intel_uncore.c


Thanks,
Namhyung