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Re: [PATCH] aarch64: Optimized memcmp for medium to large sizes
- From: Marcus Shawcroft <marcus dot shawcroft at gmail dot com>
- To: Siddhesh Poyarekar <siddhesh at sourceware dot org>
- Cc: GNU C Library <libc-alpha at sourceware dot org>, szabolcs dot nagy at arm dot com, Wilco dot Dijkstra at arm dot com
- Date: Mon, 12 Feb 2018 11:37:31 +0000
- Subject: Re: [PATCH] aarch64: Optimized memcmp for medium to large sizes
- Authentication-results: sourceware.org; auth=none
- References: <20180202045056.3121-1-siddhesh@sourceware.org>
On 2 February 2018 at 04:50, Siddhesh Poyarekar <siddhesh@sourceware.org> wrote:
> This improved memcmp provides a fast path for compares up to 16 bytes
> and then compares 16 bytes at a time, thus optimizing loads from both
> sources. The glibc memcmp microbenchmark retains performance (with an
> error of ~1ns) for smaller compare sizes and reduces up to 31% of
> execution time for compares up to 4K on the APM Mustang. On Qualcomm
> Falkor this improves to almost 48%, i.e. it is almost 2x improvement
> for sizes of 2K and above.
Hi Siddhesh,
Thanks for sharing the performance numbers on these two
u-architectures. Have you looked at the impact of this patch on
performance of the various other aarch64 u-architectures? If so
please share your findings.
Cheers
/Marcus