linux-kernel - Re: [v2] powerpc/lib: Adjust .balign inside string functions for PPC32

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Date:   Tue,  5 Jun 2018 00:10:58 +1000 (AEST)
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     Christophe Leroy <christophe.leroy@....fr>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [v2] powerpc/lib: Adjust .balign inside string functions for PPC32

On Fri, 2018-05-18 at 13:01:16 UTC, Christophe Leroy wrote:
> commit 87a156fb18fe1 ("Align hot loops of some string functions")
> degraded the performance of string functions by adding useless
> nops
> 
> A simple benchmark on an 8xx calling 100000x a memchr() that
> matches the first byte runs in 41668 TB ticks before this patch
> and in 35986 TB ticks after this patch. So this gives an
> improvement of approx 10%
> 
> Another benchmark doing the same with a memchr() matching the 128th
> byte runs in 1011365 TB ticks before this patch and 1005682 TB ticks
> after this patch, so regardless on the number of loops, removing
> those useless nops improves the test by 5683 TB ticks.
> 
> Fixes: 87a156fb18fe1 ("Align hot loops of some string functions")
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/1128bb7813a896bd608fb622eee3c2

cheers