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Re: [PATCH v3] ARM: Improve armv7 memcpy performance.
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: Will Newton <will dot newton at linaro dot org>
- Cc: <libc-ports at sourceware dot org>, <patches at linaro dot org>
- Date: Mon, 9 Sep 2013 13:39:06 +0000
- Subject: Re: [PATCH v3] ARM: Improve armv7 memcpy performance.
- Authentication-results: sourceware.org; auth=none
- References: <522D977E dot 2000906 at linaro dot org>
On Mon, 9 Sep 2013, Will Newton wrote:
> Only enter the aligned copy loop with buffers that can be 8-byte
> aligned. This improves performance slightly on Cortex-A9 and
> Cortex-A15 cores for large copies with buffers that are 4-byte
> aligned but not 8-byte aligned.
Did you conclude that the comment about needing unaligned word access for
ldrd/strd is still accurate after this patch (and if so, for which uses)?
There was a long discussion on benchmarking starting from this patch.
Could you summarise the conclusions of that discussion as they relate to
the appropriate benchmarks to apply to this patch, and give pointers to
your before-and-after performance results?
Joseph S. Myers