From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f46.google.com (mail-pa0-f46.google.com [209.85.220.46]) by kanga.kvack.org (Postfix) with ESMTP id 4B84E6B0031 for ; Wed, 20 Nov 2013 05:21:55 -0500 (EST) Received: by mail-pa0-f46.google.com with SMTP id kl14so4773659pab.33 for ; Wed, 20 Nov 2013 02:21:54 -0800 (PST) Received: from psmtp.com ([74.125.245.170]) by mx.google.com with SMTP id bc2si13851977pad.216.2013.11.20.02.21.52 for ; Wed, 20 Nov 2013 02:21:54 -0800 (PST) Date: Wed, 20 Nov 2013 10:19:57 +0000 From: Will Deacon Subject: Re: [PATCH v6 0/5] MCS Lock: MCS lock code cleanup and optimizations Message-ID: <20131120101957.GA19352@mudshark.cambridge.arm.com> References: <1384911446.11046.450.camel@schen9-DESK> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1384911446.11046.450.camel@schen9-DESK> Sender: owner-linux-mm@kvack.org List-ID: To: Tim Chen Cc: Ingo Molnar , Andrew Morton , Thomas Gleixner , "linux-kernel@vger.kernel.org" , linux-mm , "linux-arch@vger.kernel.org" , Linus Torvalds , Waiman Long , Andrea Arcangeli , Alex Shi , Andi Kleen , Michel Lespinasse , Davidlohr Bueso , Matthew R Wilcox , Dave Hansen , Peter Zijlstra , Rik van Riel , Peter Hurley , "Paul E.McKenney" , Raghavendra K T , George Spelvin , "H. Peter Anvin" , Arnd Bergmann , Aswin Chandramouleeswaran , Scott J Norton , "Figo.zhang" Hi Tim, On Wed, Nov 20, 2013 at 01:37:26AM +0000, Tim Chen wrote: > In this patch series, we separated out the MCS lock code which was > previously embedded in the mutex.c. This allows for easier reuse of > MCS lock in other places like rwsem and qrwlock. We also did some micro > optimizations and barrier cleanup. > > The original code has potential leaks between critical sections, which > was not a problem when MCS was embedded within the mutex but needs > to be corrected when allowing the MCS lock to be used by itself for > other locking purposes. > > Proper barriers are now embedded with the usage of smp_load_acquire() in > mcs_spin_lock() and smp_store_release() in mcs_spin_unlock. See > http://marc.info/?l=linux-arch&m=138386254111507 for info on the > new smp_load_acquire() and smp_store_release() functions. > > This patches were previously part of the rwsem optimization patch series > but now we spearate them out. > > We have also added hooks to allow for architecture specific > implementation of the mcs_spin_lock and mcs_spin_unlock functions. > > Will, do you want to take a crack at adding implementation for ARM > with wfe instruction? Sure, I'll have a go this week. Thanks for keeping that as a consideration! As an aside: what are you using to test this code, so that I can make sure I don't break it? Will -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org