From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1755472Ab1ATLmz (ORCPT <rfc822;w@1wt.eu>);
	Thu, 20 Jan 2011 06:42:55 -0500
Received: from e36.co.us.ibm.com ([32.97.110.154]:47014 "EHLO
	e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1755056Ab1ATLmw (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 20 Jan 2011 06:42:52 -0500
Date: Thu, 20 Jan 2011 17:12:46 +0530
From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Nick Piggin <npiggin@kernel.dk>,
        Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
        =?iso-8859-1?Q?Am=E9rico?= Wang <xiyou.wangcong@gmail.com>,
        Eric Dumazet <dada1@cosmosbay.com>, Jan Beulich <JBeulich@novell.com>,
        Avi Kivity <avi@redhat.com>, Xen-devel <xen-devel@lists.xensource.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Linux Virtualization <virtualization@lists.linux-foundation.org>,
        Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
        kvm@vger.kernel.org, suzuki@in.ibm.com
Subject: Re: [PATCH 2/3] kvm hypervisor : Add hypercalls to support
 pv-ticketlock
Message-ID: <20110120114246.GA11177@linux.vnet.ibm.com>
Reply-To: vatsa@linux.vnet.ibm.com
References: <cover.1289940821.git.jeremy.fitzhardinge@citrix.com>
 <20110119164432.GA30669@linux.vnet.ibm.com>
 <20110119171239.GB726@linux.vnet.ibm.com>
 <1295457672.28776.144.camel@laptop>
 <4D373340.60608@goop.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4D373340.60608@goop.org>
User-Agent: Mutt/1.5.20 (2009-06-14)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Jan 19, 2011 at 10:53:52AM -0800, Jeremy Fitzhardinge wrote:
> > The reason for wanting this should be clear I guess, it allows PI.
> 
> Well, if we can expand the spinlock to include an owner, then all this
> becomes moot...

How so? Having an owner will not eliminate the need for pv-ticketlocks
afaict. We still need a mechanism to reduce latency in scheduling the next
thread-in-waiting, which is achieved by your patches. 

- vatsa