Re: [PATCH 9/9] x86/lib/memset_64.S: Optimize memset by enhanced REP MOVSB/STOSB

From: Andi Kleen
Date: Wed May 18 2011 - 14:39:19 EST


> I use gcc 4.3.2 installed by FC10 to build kernel with defconfig. Only memcpy is built with gcc builtin and inline memcpy. All of others (i.e. memset, clear_page, memmove, and copy_user) call the kernel lib.
>
> It's easy to check this by disassembling kernel binary.

gcc has a complex set of heuristics. For example if it cannot decide
the length or the alignment it calls the kernel code. Otherwise
it inlines.

So just looking at a few examples won't give you the whole picture.

-Andi

--
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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