From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v6 05/11] pvqspinlock, x86: Allow unfair spinlock in a PV guest Date: Mon, 17 Mar 2014 19:54:47 +0100 Message-ID: <20140317185447.GM25546__42425.4053076313$1395082658$gmane$org@laptop.programming.kicks-ass.net> References: <1394650498-30118-1-git-send-email-Waiman.Long@hp.com> <1394650498-30118-6-git-send-email-Waiman.Long@hp.com> <20140313151515.GC25546@laptop.programming.kicks-ass.net> <53220F7F.2040701@hp.com> <20140314083001.GN27965@twins.programming.kicks-ass.net> <53273482.3030102@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WPch5-0006Vv-Cj for xen-devel@lists.xenproject.org; Mon, 17 Mar 2014 18:55:29 +0000 Content-Disposition: inline In-Reply-To: <53273482.3030102@hp.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Waiman Long Cc: Jeremy Fitzhardinge , Raghavendra K T , kvm@vger.kernel.org, Boris Ostrovsky , virtualization@lists.linux-foundation.org, Andi Kleen , "H. Peter Anvin" , Michel Lespinasse , Thomas Gleixner , linux-arch@vger.kernel.org, Gleb Natapov , x86@kernel.org, Ingo Molnar , xen-devel@lists.xenproject.org, "Paul E. McKenney" , Arnd Bergmann , Scott J Norton , Rusty Russell , Steven Rostedt , Chris Wright , Oleg Nesterov , Alok Kataria , Aswin Chandramouleeswaran , Chegu Vinod , linux-kernel@vger. List-Id: xen-devel@lists.xenproject.org On Mon, Mar 17, 2014 at 01:44:34PM -0400, Waiman Long wrote: > The PV ticketlock code was designed to handle lock holder preemption by > redirecting CPU resources in a preempted guest to another guest that can > better use it and then return the preempted CPU back sooner. But that's the PV code, not the unfair bit. And your fuller PV thing doesn't need the unfair option.