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Date: Thu, 06 Oct 2011 11:09:20 -0700
From: Jeremy Fitzhardinge <jeremy@goop.org>
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To: Stephan Diestelhorst <stephan.diestelhorst@amd.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Jan Beulich <JBeulich@suse.com>,
        Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
        Ingo Molnar <mingo@elte.hu>, Andi Kleen <andi@firstfloor.org>,
        Peter Zijlstra <peterz@infradead.org>, Nick Piggin <npiggin@kernel.dk>,
        the arch/x86 maintainers <x86@kernel.org>,
        "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
        Avi Kivity <avi@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>,
        KVM <kvm@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [Xen-devel] [PATCH 00/10] [PATCH RFC V2] Paravirtualized ticketlocks
References: <cover.1315878463.git.jeremy.fitzhardinge@citrix.com> <201109282008.17722.stephan.diestelhorst@amd.com> <CA+55aFwm7ESNfrHhEHrAKcjcPUq8YxtuEkJd5PzAekYo2dMYNw@mail.gmail.com> <2707952.s3VYcmPHUN@chlor> <4E8DE7F1.3050108@goop.org>
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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.

    J