Re: Fast memcpy patch

From: Cong Wang
Date: Wed Nov 23 2011 - 07:07:49 EST


On Wed, Nov 23, 2011 at 7:25 PM, N. Coesel <nico@xxxxxxxxx> wrote:
> Dear readers,
> I noticed the Linux kernel still uses a byte-by-byte copy method for memcpy.
> Since most memory allocations are aligned to the integer size of a cpu it is
> often faster to copy by using the CPU's native word size. The patch below
> does that. The code is already at work in many 16 and 32 bit embedded
> products. It should also work for 64 bit platforms. So far I only tested 16
> and 32 bit platforms.

Which arch are you referring?

At least on x86, it has optimized memcpy(), see arch/x86/lib/memcpy_32.c
and arch/x86/include/asm/string_64.h.
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