From mboxrd@z Thu Jan  1 00:00:00 1970
From: Waiman Long <waiman.long@hp.com>
Subject: Re: [PATCH RFC v6 10/11] pvqspinlock,
 x86: Enable qspinlock PV support for KVM
Date: Mon, 17 Mar 2014 13:47:30 -0400
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>, Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>, Gleb Natapov <gleb@redhat.com>, Peter Zijlstra <peterz@infradead.org>, virtualization@lists.linux-foundation.org, Andi Kleen <andi@firstfloor.org>, "H. Peter Anvin" <hpa@zytor.com>, Michel Lespinasse <walken@google.com>, Alok Kataria <akataria@vmware.com>, linux-arch@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org, Ingo Molnar <mingo@redhat.com>, xen-devel@lists.xenproject.org, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Arnd Bergmann <arnd@arndb.de>, Scott J Norton <scott.norton@hp.com>, Steven Rostedt <rostedt@goodmis.org>, Chris Wright <chrisw@sous-sol.org>, Thomas Gleixner <tglx@linutronix.de>, Aswin Chandramouleeswaran <aswin@hp.com>, Chegu Vinod <chegu_vinod@hp.com>, Boris Ostrovsky <boris.ostrovsky@oracle.com>, Oleg Nesterov <oleg@redhat.com>, linux-kernel@vger.
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On 03/14/2014 04:42 AM, Paolo Bonzini wrote:
> Il 13/03/2014 20:13, Waiman Long ha scritto:
>>>>
>>>
>>> This should also disable the unfair path.
>>>
>>> Paolo
>>>
>>
>> The unfair lock uses a different jump label and does not require any
>> special PV ops. There is a separate init function for that.
>
> Yeah, what I mean is that the patches that enable paravirtualization 
> should also take care of decreasing the unfair-lock jump label when 
> paravirtualization is enabled.
>
> Paolo

As there are people who don't like unfair lock at all, I prefer to give 
them the option to turn this on or off instead of forcing them to always 
use unfair lock in a PV guest.

-Longman