From: Segher Boessenkool <segher@kernel.crashing.org>
To: David Esparza <david.esparza.borquez@intel.com>,
gcc-patches@gcc.gnu.org, richard.sandiford@linaro.org
Subject: Re: [PATCH] Change PRED_LOOP_EXIT from 85 to 92
Date: Sun, 24 Dec 2017 12:03:00 -0000 [thread overview]
Message-ID: <20171224120327.GH10515@gate.crashing.org> (raw)
In-Reply-To: <87po74ebfr.fsf@linaro.org>
On Sun, Dec 24, 2017 at 09:12:56AM +0000, Richard Sandiford wrote:
> Segher Boessenkool <segher@kernel.crashing.org> writes:
> > On Fri, Dec 22, 2017 at 04:53:47PM -0600, David Esparza wrote:
> >> With a value of 85 GCC has a CPU performance degradation of 11%,
> >> reverting PRED_LOOP_EXIT to 92 this degradation disappear.
> >> Those values where measured by running c-ray ray-tracer that is a
> >> floating point benchmark that runs out of L1 cache.
> >
> > Why is this single benchmark more important than everything else?
> >
> > https://patchwork.ozlabs.org/patch/637073/
>
> "Everything" else? :-) It sounds from Andrew's reply like it wasn't
> a win on other benchmarks too.
Yeah... But at least Martin tested spec2006, instead of one single
tiny non-representative program.
> Neither covering message has really explained why the previous value was
> too low/high, but maybe that's just the way it goes with these tuning
> parameters...
It would be nice if they explained how they tested things.
Segher
next prev parent reply other threads:[~2017-12-24 12:03 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-22 22:49 David Esparza
2017-12-23 22:08 ` Segher Boessenkool
2017-12-24 9:13 ` Richard Sandiford
2017-12-24 12:03 ` Segher Boessenkool [this message]
2017-12-24 18:58 ` Jeff Law
2018-01-02 11:57 ` Martin Liška
2018-01-02 16:37 ` Jeff Law
2018-01-22 8:57 ` Martin Liška
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