linux-kernel - Re: [PATCH] expand micro-optimizations in kernel to newer model CPUs

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Date:	Sun, 15 Dec 2013 14:23:29 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	John <da_audiophile@...oo.com>
Cc:	Richard Weinberger <richard.weinberger@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"david.heidelberger@...t.cz" <david.heidelberger@...t.cz>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] expand micro-optimizations in kernel to newer model CPUs

On Sun, Dec 15, 2013 at 04:42:50AM -0800, John wrote:
> I am using ANOVA to establish that the generic group differs from the
> optimized group.

You probably should run a couple other benchmarks, in addition, for
greater confidence that this optimization actually brings any palpable
improvement and is not just causing code bloat.

For example, last time I did a perf profile of a kernel build on AMD
F15h, the PILERDRIVER "optimization" was actually even a bit worse than
the standard MK8 one.

http://marc.info/?l=linux-kernel&m=138081947417204

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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