Am Mi 28.12.2005 19:11 schrieb Bryan O'Sullivan <[email protected]>:
> 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 you test the C version use
CFLAGS_memcpy32.o := -funroll-loops
BTW on x86-64 with CONFIG_UNORDERED_IO writel can actually expand to a
non temporal write which might break it.
-Andi
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