Re: [PATCH] perf, x86: Enable PEBS mode automatically formem-{loads,stores} v3

From: Peter Zijlstra
Date: Tue Jul 23 2013 - 12:58:04 EST


On Tue, Jul 23, 2013 at 06:13:34PM +0200, Andi Kleen wrote:
> On Tue, Jul 23, 2013 at 10:38:34AM +0200, Peter Zijlstra wrote:
> > On Thu, Jul 18, 2013 at 04:03:39PM -0700, Andi Kleen wrote:
> > > From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> > >
> > > [The patch to enable this in the user tools has been sent separately]
> > >
> > > With the earlier patches to automatically try cpu// and add
> > > a precise sys attribute, we can now enable PEBS for the mem-loads,
> > > mem-stores events everywhere.
> > >
> > > This allows to use
> > >
> > > perf record -e mem-loads ...
> > >
> > > instead of
> > >
> > > perf record -e cpu/mem-loads/p ...
> > >
> > > Always use precise=2 even though it is costly pre-Haswell
> >
> > This Changelog fails to give a reason _why_ we'd want to do this.
>
> The first is much nicer to type and understand? Just in the spirit of
> making perf easier to use.

And here I was thinking that maybe these events don't make sense without
pebs or so. But no, rather than giving an actual useful reason you'd
have me look things up myself. *sigh*
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