Message-ID: <517595FA.800@redhat.com>
Date: Mon, 22 Apr 2013 15:56:42 -0400
From: Rik van Riel <riel@redhat.com>
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To: Peter Zijlstra <peterz@infradead.org>
CC: Jiannan Ouyang <ouyang@cs.pitt.edu>, LKML <linux-kernel@vger.kernel.org>,
        Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
        Avi Kivity <avi.kivity@gmail.com>, Gleb Natapov <gleb@redhat.com>,
        Ingo Molnar <mingo@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>,
        Srikar <srikar@linux.vnet.ibm.com>, "H. Peter Anvin" <hpa@zytor.com>,
        "Nikunj A. Dadhania" <nikunj@linux.vnet.ibm.com>,
        KVM <kvm@vger.kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
        Chegu Vinod <chegu_vinod@hp.com>,
        "Andrew M. Theurer" <habanero@linux.vnet.ibm.com>,
        Srivatsa Vaddagiri <srivatsa.vaddagiri@gmail.com>,
        Andrew Jones <drjones@redhat.com>, Karen Noel <knoel@redhat.com>
Subject: Re: Preemptable Ticket Spinlock
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On 04/22/2013 03:49 PM, Peter Zijlstra wrote:
> On Mon, 2013-04-22 at 08:52 -0400, Rik van Riel wrote:

>> If the native spin_lock code has been called already at
>> that time, the native code would still need to be modified
>> to increment the ticket number by 2, so we end up with a
>> compatible value in each spin lock's .tickets field, and
>> prevent a deadlock after we switch over to the paravirt
>> variant.
>
> I thought the stuff already made it upstream, but apparently not; the
> lastest posting I'm aware of is here:
>
>    https://lkml.org/lkml/2012/5/2/105
>
> That stuff changes the normal ticket increment as well..

Jiannan,

It looks like the patch above could make a good patch
1 (or 2) in your patch series :)

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