Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754183AbaBRHbf (ORCPT ); Tue, 18 Feb 2014 02:31:35 -0500 Received: from merlin.infradead.org ([205.233.59.134]:36331 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751239AbaBRHbd (ORCPT ); Tue, 18 Feb 2014 02:31:33 -0500 Date: Tue, 18 Feb 2014 08:31:11 +0100 From: Peter Zijlstra To: "H. Peter Anvin" Cc: Waiman Long , Thomas Gleixner , Ingo Molnar , Arnd Bergmann , linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Steven Rostedt , Andrew Morton , Michel Lespinasse , Andi Kleen , Rik van Riel , "Paul E. McKenney" , Linus Torvalds , Raghavendra K T , George Spelvin , Tim Chen , Daniel J Blueman , Alexander Fyodorov , Aswin Chandramouleeswaran , Scott J Norton , Thavatchai Makphaibulchoke Subject: Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock Message-ID: <20140218073111.GW27965@twins.programming.kicks-ass.net> References: <1392669684-4807-1-git-send-email-Waiman.Long@hp.com> <53029167.4060109@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53029167.4060109@zytor.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 17, 2014 at 02:47:03PM -0800, H. Peter Anvin wrote: > On 02/17/2014 12:41 PM, Waiman Long wrote: > > v3->v4: > > - Remove debugging code and fix a configuration error > > - Simplify the qspinlock structure and streamline the code to make it > > perform a bit better > > - Add an x86 version of asm/qspinlock.h for holding x86 specific > > optimization. > > - Add an optimized x86 code path for 2 contending tasks to improve > > low contention performance. > > > > v2->v3: > > - Simplify the code by using numerous mode only without an unfair option. > > - Use the latest smp_load_acquire()/smp_store_release() barriers. > > - Move the queue spinlock code to kernel/locking. > > - Make the use of queue spinlock the default for x86-64 without user > > configuration. > > - Additional performance tuning. > > > > v1->v2: > > - Add some more comments to document what the code does. > > - Add a numerous CPU mode to support >= 16K CPUs > > - Add a configuration option to allow lock stealing which can further > > improve performance in many cases. > > - Enable wakeup of queue head CPU at unlock time for non-numerous > > CPU mode. > > > > This patch set introduces a queue-based spinlock implementation that > > can replace the default ticket spinlock without increasing the size > > of the spinlock data structure. As a result, critical kernel data > > structures that embed spinlock won't increase in size and breaking > > data alignments. > > > > This is starting to look good, so I have pulled it into > tip:x86/spinlocks to start give it some testing mileage. It very much needs paravirt muck before we can even consider it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/