Re: [PATCH 1/1] perf, Add support for Xeon-Phi PMU

From: Cyrill Gorcunov
Date: Tue Sep 25 2012 - 08:23:16 EST


On Tue, Sep 25, 2012 at 04:22:29PM +0400, Cyrill Gorcunov wrote:
> On Tue, Sep 25, 2012 at 02:05:58PM +0200, stephane eranian wrote:
> > On Tue, Sep 25, 2012 at 2:01 PM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> > > On Tue, 2012-09-25 at 15:42 +0400, Cyrill Gorcunov wrote:
> > >
> > >> Guys, letme re-read this whole mail thread first since I have no clue
> > >> what this remapping about ;)
> > >
> > > x86_setup_perfctr() / set_ext_hw_attr() have special purposed 0 and -1
> > > config values to mean -ENOENT and -EINVAL resp.
> > >
> > > This means neither config value can be a 'real' event. Now it turns out
> > > Xeon-Phi has an actual event 0, which is masked by these special case
> > > thingies.
> >
> > Then how about using -1 or -2 for ENOENT and EINVAL?
>
> -2 can't be a valid p4 config as far as i can tell.

I mean such value can be easily recognized by p4 code and treated
specially if needed.
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