From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v12 09/11] pvqspinlock, x86: Add para-virtualization support Date: Sat, 25 Oct 2014 00:04:23 +0200 Message-ID: <20141024220423.GB10501@worktop.programming.kicks-ass.net> References: <1413483040-58399-1-git-send-email-Waiman.Long@hp.com> <1413483040-58399-10-git-send-email-Waiman.Long@hp.com> <20141024084738.GU21513@worktop.programming.kicks-ass.net> <544ABC47.2000700@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: <544ABC47.2000700@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 Fri, Oct 24, 2014 at 04:53:27PM -0400, Waiman Long wrote: > The additional register pressure may just cause a few more register moves > which should be negligible in the overall performance . The additional > icache pressure, however, may have some impact on performance. I was trying > to balance the performance of the pv and non-pv versions so that we won't > penalize the pv code too much for a bit more performance in the non-pv code. > Doing it your way will add a lot of function call and register > saving/restoring to the pv code. If people care about performance they should not be using virt crap :-) I only really care about bare metal. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:55302 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755126AbaJXWEe (ORCPT ); Fri, 24 Oct 2014 18:04:34 -0400 Date: Sat, 25 Oct 2014 00:04:23 +0200 From: Peter Zijlstra Subject: Re: [PATCH v12 09/11] pvqspinlock, x86: Add para-virtualization support Message-ID: <20141024220423.GB10501@worktop.programming.kicks-ass.net> References: <1413483040-58399-1-git-send-email-Waiman.Long@hp.com> <1413483040-58399-10-git-send-email-Waiman.Long@hp.com> <20141024084738.GU21513@worktop.programming.kicks-ass.net> <544ABC47.2000700@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <544ABC47.2000700@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: <20141024220423.2nZkdEjYRQ6qivuvKy_V6vlpM2u5g_F_uQxLl98MWlM@z> On Fri, Oct 24, 2014 at 04:53:27PM -0400, Waiman Long wrote: > The additional register pressure may just cause a few more register moves > which should be negligible in the overall performance . The additional > icache pressure, however, may have some impact on performance. I was trying > to balance the performance of the pv and non-pv versions so that we won't > penalize the pv code too much for a bit more performance in the non-pv code. > Doing it your way will add a lot of function call and register > saving/restoring to the pv code. If people care about performance they should not be using virt crap :-) I only really care about bare metal.