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Date: Tue, 3 Dec 2002 15:55:29 +0000
From: Dave Jones <davej@codemonkey.org.uk>
To: "Calin A. Culianu" <calin@ajvar.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: SMP Pentium4 -- PAUSE Instruction
Message-ID: <20021203155529.GA1622@suse.de>
Mail-Followup-To: Dave Jones <davej@codemonkey.org.uk>,
	"Calin A. Culianu" <calin@ajvar.org>,
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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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