Linux-kernel mailing list archive 2000-23,: Re: [PATCH] ac7 Athlon-SMP

# Re: [PATCH] ac7 Athlon-SMP

Tom Leete (tleete@mountain.net)
Mon, 05 Jun 2000 05:38:39 -0400

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willy@thepuffingroup.com wrote:
>
> On Sat, Jun 03, 2000 at 08:55:52AM -0400, Tom Leete wrote:
> > Hello,
> >
> > Here is a fix for the K7-SMP compilation failures I reported yesterday.
> >
> > The memcpy3d functions are moved to arch/i386/lib/mmx.c with the
> > corresponding changes to asm-i386/mmx.h. This also allowed a cleanup
> > of asm-i386/string.h.
>
> this cannot be acceptable. you've turned two inline functions into function
> calls -- and memcpy has to be fast.
>

I have checked the costs and benefits of inlining memcpy. The memcpy3d functions consist
of about 40 machine instructions taking up 110 bytes.

Athlon docs recommend inlining for less than 25 machine instructions.

$ objdump -d vmlinux | grep memcpy -- | wc
430 3709 28419

so inlining them would cost 412*110 or 45k.

Who is the author/maintainer of the Athlon code? I don't see any reference in the source
or the kernel docs.

Tom

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