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Re: [PATCH] aarch64: Increase small and medium cases for __memcpy_generic
- From: Szabolcs Nagy <Szabolcs dot Nagy at arm dot com>
- To: Krzysztof Koch <Krzysztof dot Koch at arm dot com>, "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>
- Cc: nd <nd at arm dot com>
- Date: Tue, 12 Nov 2019 17:09:29 +0000
- Subject: Re: [PATCH] aarch64: Increase small and medium cases for __memcpy_generic
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On 05/11/2019 17:35, Krzysztof Koch wrote:
> Increase the upper bound on medium cases from 96 to 128 bytes.
> Now, up to 128 bytes are copied unrolled.
>
> Increase the upper bound on small cases from 16 to 32 bytes so that
> copies of 17-32 bytes are not impacted by the larger medium case.
>
> Benchmarking:
> The attached figures show relative timing difference with respect
> to 'memcpy_generic', which is the existing implementation.
> 'memcpy_med_128' denotes the the version of memcpy_generic with
> only the medium case enlarged. The 'memcpy_med_128_small_32' numbers
> are for the version of memcpy_generic submitted in this patch, which
> has both medium and small cases enlarged. The figures were generated
> using the script from:
> https://www.sourceware.org/ml/libc-alpha/2019-10/msg00563.html
>
> Depending on the platform, the performance improvement in the
> bench-memcpy-random.c benchmark ranges from 6% to 20% between
> the original and final version of memcpy.S
>
> Tested against GLIBC testsuite and randomized tests.
> ---
> sysdeps/aarch64/memcpy.S | 82 +++++++++++++++++++++++++++---------------------
> 1 file changed, 47 insertions(+), 35 deletions(-)
thanks, committed.