Messages in this thread | | | Subject | Re: [RFC] [PATCH] Add memcpy32 function | From | Bryan O'Sullivan <> | Date | Wed, 28 Dec 2005 10:11:43 -0800 |
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On Wed, 2005-12-28 at 18:50 +0100, Andreas Kleen wrote:
> Ok thanks. And do you have numbers that show that the assembly > function with rep ; movsl actually improves performance over C?
I'll see if I can ferret some numbers out. If not, I'll generate them, but it will take me a day or so. I'm pretty sure it makes a difference of tens to hundreds of nanoseconds, which in our case is very significant (we measure some of our user-level performance in increments of 10ns, very repeatably).
> If the assembly is not really faster I would recommend you just use a > writel() > loop in the driver instead of adding this very special purpose function > everywhere.
Yeah, clearly if there's no difference, it's not worth the trouble.
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