linux-kernel - Re: [Xen-devel] [PATCH 00/10] [PATCH RFC V2] Paravirtualized ticketlocks

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Date:	Mon, 10 Oct 2011 09:32:14 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Stephan Diestelhorst <stephan.diestelhorst@....com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>, Jan Beulich <JBeulich@...e.com>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>,
	Andi Kleen <andi@...stfloor.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Nick Piggin <npiggin@...nel.dk>,
	the arch/x86 maintainers <x86@...nel.org>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	Avi Kivity <avi@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	KVM <kvm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: Re: [Xen-devel] [PATCH 00/10] [PATCH RFC V2] Paravirtualized
 ticketlocks


* Jeremy Fitzhardinge <jeremy@...p.org> wrote:

> On 10/06/2011 10:40 AM, Jeremy Fitzhardinge wrote:
> > However, it looks like locked xadd is also has better performance:  on
> > my Sandybridge laptop (2 cores, 4 threads), the add+mfence is 20% slower
> > than locked xadd, so that pretty much settles it unless you think
> > there'd be a dramatic difference on an AMD system.
> 
> Konrad measures add+mfence is about 65% slower on AMD Phenom as well.

xadd also results in smaller/tighter code, right?

Thanks,

	Ingo
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