From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v12 00/11] qspinlock: a 4-byte queue spinlock with PV support Date: Fri, 24 Oct 2014 10:57:00 +0200 Message-ID: <20141024085659.GW21513@worktop.programming.kicks-ass.net> References: <1413483040-58399-1-git-send-email-Waiman.Long@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1413483040-58399-1-git-send-email-Waiman.Long@hp.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Waiman Long Cc: linux-arch@vger.kernel.org, Rik van Riel , Raghavendra K T , Oleg Nesterov , kvm@vger.kernel.org, Konrad Rzeszutek Wilk , Scott J Norton , x86@kernel.org, Paolo Bonzini , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Ingo Molnar , David Vrabel , "H. Peter Anvin" , xen-devel@lists.xenproject.org, Thomas Gleixner , "Paul E. McKenney" , Linus Torvalds , Boris Ostrovsky , Douglas Hatch List-Id: linux-arch.vger.kernel.org On Thu, Oct 16, 2014 at 02:10:29PM -0400, Waiman Long wrote: > v11->v12: > - Based on PeterZ's version of the qspinlock patch > (https://lkml.org/lkml/2014/6/15/63). > - Incorporated many of the review comments from Konrad Wilk and > Paolo Bonzini. > - The pvqspinlock code is largely from my previous version with > PeterZ's way of going from queue tail to head and his idea of > using callee saved calls to KVM and XEN codes. Thanks for taking the time to refresh this.. I would prefer you use a little more of the PV techniques I outlined in my latest PV patch to further reduce the overhead of PV enabled kernels on real hardware. This is an important use case, because distro kernels will have to enable PV support while their majority of installations will be on physical hardware. Other than that I see no reason not to move this forward. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:37534 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751690AbaJXI5L (ORCPT ); Fri, 24 Oct 2014 04:57:11 -0400 Date: Fri, 24 Oct 2014 10:57:00 +0200 From: Peter Zijlstra Subject: Re: [PATCH v12 00/11] qspinlock: a 4-byte queue spinlock with PV support Message-ID: <20141024085659.GW21513@worktop.programming.kicks-ass.net> References: <1413483040-58399-1-git-send-email-Waiman.Long@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1413483040-58399-1-git-send-email-Waiman.Long@hp.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Waiman Long Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, kvm@vger.kernel.org, Paolo Bonzini , Konrad Rzeszutek Wilk , Boris Ostrovsky , "Paul E. McKenney" , Rik van Riel , Linus Torvalds , Raghavendra K T , David Vrabel , Oleg Nesterov , Scott J Norton , Douglas Hatch Message-ID: <20141024085700.iBxTbZABsdseRkcsH2DYY7Y9AiiX1ZZJMvIe5QOoMS4@z> On Thu, Oct 16, 2014 at 02:10:29PM -0400, Waiman Long wrote: > v11->v12: > - Based on PeterZ's version of the qspinlock patch > (https://lkml.org/lkml/2014/6/15/63). > - Incorporated many of the review comments from Konrad Wilk and > Paolo Bonzini. > - The pvqspinlock code is largely from my previous version with > PeterZ's way of going from queue tail to head and his idea of > using callee saved calls to KVM and XEN codes. Thanks for taking the time to refresh this.. I would prefer you use a little more of the PV techniques I outlined in my latest PV patch to further reduce the overhead of PV enabled kernels on real hardware. This is an important use case, because distro kernels will have to enable PV support while their majority of installations will be on physical hardware. Other than that I see no reason not to move this forward.