From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752676AbaBRTap (ORCPT ); Tue, 18 Feb 2014 14:30:45 -0500 Received: from g9t1613g.houston.hp.com ([15.240.0.71]:41145 "EHLO g9t1613g.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752472AbaBRTan (ORCPT ); Tue, 18 Feb 2014 14:30:43 -0500 Message-ID: <5303B4C4.2040907@hp.com> Date: Tue, 18 Feb 2014 14:30:12 -0500 From: Waiman Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12 MIME-Version: 1.0 To: Peter Zijlstra CC: "H. Peter Anvin" , 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 References: <1392669684-4807-1-git-send-email-Waiman.Long@hp.com> <53029167.4060109@zytor.com> <20140218073111.GW27965@twins.programming.kicks-ass.net> In-Reply-To: <20140218073111.GW27965@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/18/2014 02:31 AM, Peter Zijlstra wrote: > 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. I will start looking at how to make it work with paravirt. Hopefully, it won't take too long. -Longman