[PATCH 4/4] Add make autoprofiledbootstrap

Andi Kleen ak@linux.intel.com
Wed Apr 27 16:27:00 GMT 2016


On Wed, Apr 27, 2016 at 05:36:09PM +0200, Bernd Schmidt wrote:
> On 03/28/2016 06:44 AM, Andi Kleen wrote:
> >From: Andi Kleen <ak@linux.intel.com>
> >
> >Add support for profiledbootstrap with autofdo. Will be useful
> >to get better testing coverage of autofdo.
> 
> Is this the only purpose? I'll admit this is the patch I like least out of
> the series.

It's the main purpose, since we already have profiled feedback. 
bootstrap is one of the best tests we have and autofdo badly needs it.

It's also a useful benchmark, so if autofdo gets improved it can catch up more
with explicit profiling.

> >The autofdo'ed compiler is ~7% faster on insn-recog.i (vs ~11% for
> >profiledfeedback), and ~4% faster for tramp3d-v4 (vs 10% for
> >profiledfeedback)
> 
> So it seems like we get worse results than with a feature we already have,
> so I don't quite see the value.

I hope as it gets tuned that will improve. Also autofdo is so much
easier to use on other software that the main usage elsewhere may well be autofdo,
not explicit instrumentation.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only



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