Re: [BK+PATCH] remove __constant_memcpy

H. Peter Anvin (hpa@zytor.com)
17 Apr 2003 17:29:23 -0700

Followup to: <Pine.LNX.4.44.0304171654530.14595-100000@home.transmeta.com>
By author: Linus Torvalds <torvalds@transmeta.com>
In newsgroup: linux.dev.kernel
>
> > 2) why no sse2-optimized memcpy? just that noone has done one yet?
>
> Yes. If you want to, it's definitely the right thing to do. More so than
> the 3dnow stuff that is by now ancient. HOWEVER, I don't think there are
> any really valid large memcpy() calls inside the kernel. All the valid
> ones are either special-cased (ie "copy_page()") or to user space.
>

It's questionable, though, if SSE-2 buys you anything SSE-1 doesn't
already have. SSE-2 is basically integer and scalar ops for SSE, but
data moving and even XOR is perfectly well handled by SSE-1.

-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
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