Messages in this thread | | | Date | Thu, 17 Apr 2003 16:59:55 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [BK+PATCH] remove __constant_memcpy |
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On Thu, 17 Apr 2003, Jeff Garzik wrote: > > If DTRT means just using the existing code for large copies in general, > that's easy enough... patch attached.
Yeah, this looks more palatable. It gets rid of a rather ugly thing, with no loss in generality _and_ if gcc ever tries to use sse2 for small copies, we can file that as a valid bug (there's just no way it's a good idea considering the costs of FP state even in user space)
> 1) where did the 486 string ops go?
They were disabled forever, because nobody cared enough, and they had known (or at least strongly suspected) bugs.
> 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.
So I wouldn't worry about it at a memcpy() level.
Linus
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