Messages in this thread | | | Date | Mon, 08 Feb 2010 14:33:06 +0100 | From | Artur Skawina <> | Subject | Re: x86 - cpu_relax - why nop vs. pause? |
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Michael Breuer wrote: > Just to move away from this... totally perplexed, I retested a bit. > Seems something else had gone wrong causing me to try 'rep;pause' vs. > 'pause'. The resulting opcode is f3 f3 90, as noted above. > > I do see what seems to be a small but noticeable performance improvement > - no idea if there's a downside, and also no idea what f3 f3 90 does vs. > f3 90. Might be something interesting, or maybe not.
Alignment? IOW what happens if you use eg "nop; rep; nop;" or "rep; nop; nop;"?
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