Messages in this thread | | | Date | Sat, 13 Oct 2012 01:17:19 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH RFC 2/2] [x86] Optimize copy_page by re-arranging instruction sequence and saving register |
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On Fri, Oct 12, 2012 at 05:02:57PM -0400, George Spelvin wrote: > Here are some Phenom results for that benchmark. The average time > increases from 700 to 760 cycles (+8.6%).
I was afraid something like that would show up.
Btw, in looking at this more and IINM, we use the REP MOVSQ version on AMD anyway because of X86_FEATURE_REP_GOOD being set on some K8 and everything from F10h on.
So, actually this µbenchmark should be comparing the REP MOVSQ case too and the changes to the unrolled copy_page shouldn't concern AMD boxes actually...
Hmm.
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