Re: SMP Pentium4 -- PAUSE Instruction
Dave Jones (davej@codemonkey.org.uk)
Tue, 3 Dec 2002 15:55:29 +0000
On Tue, Dec 03, 2002 at 10:42:13AM -0500, Calin A. Culianu wrote:
>
> I as wondering -- according to Intel's docs they recommend that on a P4
> processor to use the PAUSE instruction (aka rep followed by a nop) inside
> any spin loop (such as one used in SMP spinlock code) in order to both
> improve processor performance and reduce power consumption.
> Is this instruction being used in spin-wait loops? For some reason, I am
> having a hard time figuring out whether or not it is being used. There is
> a rep_nop() in processor.h.. but I can't determine if that is being called
> for spin lock lock/unlock code.
there's also rep;nop in asm-i386/spinlock.h
See spin_lock_string()
Dave
--
| Dave Jones. http://www.codemonkey.org.uk
| SuSE Labs
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