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Re: [Xen-devel] [PATCH] x86: adjust placement of pause insn in _raw_spin
| To: | Jan Beulich <jbeulich@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] [PATCH] x86: adjust placement of pause insn in _raw_spin_lock() |
| From: | Keir Fraser <keir.fraser@xxxxxxxxxxxxx> |
| Date: | Fri, 08 Aug 2008 15:02:55 +0100 |
| Cc: | |
| Delivery-date: | Fri, 08 Aug 2008 07:03:31 -0700 |
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| In-reply-to: | <C4C204D9.2544D%keir.fraser@xxxxxxxxxxxxx> |
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| Thread-index: | Acj5WG/ormbFmmVLEd2xugAX8io7RQABwR9E |
| Thread-topic: | [Xen-devel] [PATCH] x86: adjust placement of pause insn in _raw_spin_lock() |
| User-agent: | Microsoft-Entourage/11.4.0.080122 |
Ah, I suppose it reduce lock acquisition latency slightly. I'll apply it. -- Keir On 8/8/08 14:12, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote: > Why? > > -- Keir > > On 8/8/08 13:49, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote: > >> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx> >> >> Index: 2008-08-06/xen/include/asm-x86/spinlock.h >> =================================================================== >> --- 2008-08-06.orig/xen/include/asm-x86/spinlock.h 2007-09-10 >> 09:59:37.000000000 +0200 >> +++ 2008-08-06/xen/include/asm-x86/spinlock.h 2008-08-07 12:36:13.000000000 >> +0200 >> @@ -23,8 +23,8 @@ static inline void _raw_spin_lock(spinlo >> "1: lock; decb %0 \n" >> " js 2f \n" >> ".section .text.lock,\"ax\"\n" >> - "2: cmpb $0,%0 \n" >> - " rep; nop \n" >> + "2: rep; nop \n" >> + " cmpb $0,%0 \n" >> " jle 2b \n" >> " jmp 1b \n" >> ".previous" >> >> >> >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@xxxxxxxxxxxxxxxxxxx >> http://lists.xensource.com/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel |
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