Re: [PATCH] x86, perf: Use INST_RETIRED.PREC_DIST for cycles:pp on Skylake

[Andi Kleen]

On Wed, Oct 21, 2015 at 06:52:52PM +0200, Peter Zijlstra wrote:
> On Wed, Oct 21, 2015 at 08:26:08AM -0700, Andi Kleen wrote:
> > So it turns out that UOPS_RETIRED.ALL+pebs only works by accident
> > on Skylake. It's not in the specification.
> 
> Accident or not, it works and you've tested it. Might as well keep it.
> Specs can be updated.

No, it's better not to use it.

> Also, even with the SNB 'hickup' they still haven't got the memo that
> cycles is important for PEBS ?

INST_RETIRED.PREC_DIST is a far better cycles than UOPS_RETIRED.ALL
(see my earlier example)

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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