From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH 04/11] qspinlock: Extract out the exchange of tail code word Date: Tue, 24 Jun 2014 12:47:02 +0200 Message-ID: <20140624104702.GO13930@laptop.programming.kicks-ass.net> References: <20140615124657.264658593@chello.nl> <20140615130153.376621956@chello.nl> <20140617205525.GB29634@laptop.dumpdata.com> <53A17A09.6010007@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <53A17A09.6010007@redhat.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: Paolo Bonzini Cc: Waiman.Long@hp.com, linux-arch@vger.kernel.org, riel@redhat.com, gleb@redhat.com, kvm@vger.kernel.org, Konrad Rzeszutek Wilk , boris.ostrovsky@oracle.com, scott.norton@hp.com, raghavendra.kt@linux.vnet.ibm.com, paolo.bonzini@gmail.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, chegu_vinod@hp.com, david.vrabel@citrix.com, oleg@redhat.com, xen-devel@lists.xenproject.org, tglx@linutronix.de, paulmck@linux.vnet.ibm.com, torvalds@linux-foundation.org, mingo@kernel.org List-Id: linux-arch.vger.kernel.org On Wed, Jun 18, 2014 at 01:37:45PM +0200, Paolo Bonzini wrote: > However, I *do* agree with you that it's simpler to just squash this patch > into 01/11. So I explicitly broke out these optimizations into separate patches so that we can see them independently and agree they're idempotent wrt the state machine. The initial patches by Waiman were totally unreadable, partly because the optimizations made the code terribly complex. Luckily waiman then dropped the most horrible optimizations (optimization for the very large nr_cpus case, were we cannot have a pending byte), so the end result isn't quite as complex as it used to be. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:44269 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751407AbaFXKrP (ORCPT ); Tue, 24 Jun 2014 06:47:15 -0400 Date: Tue, 24 Jun 2014 12:47:02 +0200 From: Peter Zijlstra Subject: Re: [PATCH 04/11] qspinlock: Extract out the exchange of tail code word Message-ID: <20140624104702.GO13930@laptop.programming.kicks-ass.net> References: <20140615124657.264658593@chello.nl> <20140615130153.376621956@chello.nl> <20140617205525.GB29634@laptop.dumpdata.com> <53A17A09.6010007@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53A17A09.6010007@redhat.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Paolo Bonzini Cc: Konrad Rzeszutek Wilk , Waiman.Long@hp.com, tglx@linutronix.de, mingo@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, kvm@vger.kernel.org, paolo.bonzini@gmail.com, boris.ostrovsky@oracle.com, paulmck@linux.vnet.ibm.com, riel@redhat.com, torvalds@linux-foundation.org, raghavendra.kt@linux.vnet.ibm.com, david.vrabel@citrix.com, oleg@redhat.com, gleb@redhat.com, scott.norton@hp.com, chegu_vinod@hp.com Message-ID: <20140624104702.OrPM44DehMjF_6Hwij_gZ9LeBTmTOLOI1Bg9UrOgMqg@z> On Wed, Jun 18, 2014 at 01:37:45PM +0200, Paolo Bonzini wrote: > However, I *do* agree with you that it's simpler to just squash this patch > into 01/11. So I explicitly broke out these optimizations into separate patches so that we can see them independently and agree they're idempotent wrt the state machine. The initial patches by Waiman were totally unreadable, partly because the optimizations made the code terribly complex. Luckily waiman then dropped the most horrible optimizations (optimization for the very large nr_cpus case, were we cannot have a pending byte), so the end result isn't quite as complex as it used to be.