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Re: [PATCH 3/3] powerpc: Use default st{r,p}cpy optimization for POWER7
- From: Steven Munroe <munroesj at linux dot vnet dot ibm dot comcom>
- To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- Cc: GNU C Library <libc-alpha at sourceware dot org>, Tulio Magno Quites Machado Filho <tuliom at linux dot vnet dot ibm dot com>, OndÅej BÃlka <neleai at seznam dot cz>
- Date: Wed, 29 Jul 2015 09:12:58 -0500
- Subject: Re: [PATCH 3/3] powerpc: Use default st{r,p}cpy optimization for POWER7
- Authentication-results: sourceware.org; auth=none
- References: <55B823B2 dot 6060708 at linaro dot org>
- Reply-to: munroesj at linux dot vnet dot ibm dot com
On Tue, 2015-07-28 at 21:52 -0300, Adhemerval Zanella wrote:
> Following the discussion with Ondrej and recent changes to default
> st{r,á}cpy algorithm, this patches uses it for both powerpc64 and
> powerpc64/power7 instead of optimized ones (which will be removed).
> This is faster in all but few inputs (mostly with very short sizes)
> for benchtests.
>
> It removes the default powerpc64 st{r,p}cpy and uses the same
> optimization, since powerpc64 optimized algorithm only uses a
> slight optimized path for both doubleword aligned source and
> destiny and resorting to byte-per-byte access to unaligned inputs.
>
Hold off for bit on this. There is some concern that the benchmark used
to justify this optimization may not be representative. We need time to
review the code and the benchmark before accepting this change.