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Date: Thu, 20 Jan 2011 09:52:21 +0000
From: "Jan Beulich" <JBeulich@novell.com>
To: "Jeremy Fitzhardinge" <jeremy@goop.org>
Cc: "Jeremy Fitzhardinge" <jeremy.fitzhardinge@citrix.com>,
        "Eric Dumazet" <dada1@cosmosbay.com>, <xiyou.wangcong@gmail.com>,
        <suzuki@in.ibm.com>, "Peter Zijlstra" <peterz@infradead.org>,
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        "Linux Virtualization" <virtualization@lists.linux-foundation.org>,
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        "Mathieu Desnoyers" <mathieu.desnoyers@polymtl.ca>,
        "Avi Kivity" <avi@redhat.com>,
        "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH 13/14] x86/ticketlock: add slowpath logic
References: <cover.1289940821.git.jeremy.fitzhardinge@citrix.com>
 <97ed99ae9160bdb6477284b333bd6708fb7a19cb.1289940821.git.jeremy.fitzhardinge@citrix.com>
 <20110117152222.GA19233@linux.vnet.ibm.com> <4D372DEA.1060004@goop.org>
 <20110119183914.GB7235@linux.vnet.ibm.com> <4D37338E.8030509@goop.org>
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>>> On 19.01.11 at 19:55, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> On 01/19/2011 10:39 AM, Srivatsa Vaddagiri wrote:
>> I have tested quite extensively with booting a 16-vcpu guest (on a 16-pcpu 
> host)
>> and running kernel compine (with 32-threads). Without this patch, I had
>> difficulty booting/shutting-down successfully (it would hang mid-way).
> 
> Sounds good.  But I like to test with "make -j 100-200" to really give
> things a workout.

Hmm, in my experience, heavily over-committing CPUs (e.g. a
domain with double or more the vCPU-s that the system has
pCPU-s, or the pCPU-s the domain is allowed to run on) is a
much better test for eventual problems in the spin lock code
paths.

Jan