Re: [PATCH v2 2/2] perf tools: Make Power7 events available for perf

From: Michael Ellerman
Date: Thu Jul 11 2013 - 02:58:16 EST


On Thu, Jul 11, 2013 at 12:42:31AM -0400, Vince Weaver wrote:
> On Wed, 10 Jul 2013, Ingo Molnar wrote:
>
> > Exactly - PMUs enumerated in /sys should be self-identifying, it's a
> > hardware topology after all ...
> >
> > Anytime userspace is forced to look into /proc, or into weird places in
> > /sys it's a FAIL really.
>
> well on x86 you have to look at /proc/cpuinfo to get the
> vendor/family/model number. Should we add some specifier under sys?
> It's probably too late though as all userspace event libs will have
> to look at /proc/cpuinfo anyway to be backwards compatible.

If it's a new library implementing a new feature then no I don't think
it needs to be backward compatible. It's just a choice the library makes
as to what extent it depends on new kernel features.

cheers
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