From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f43.google.com (mail-pa0-f43.google.com [209.85.220.43]) by kanga.kvack.org (Postfix) with ESMTP id 716AB6B0036 for ; Wed, 20 Nov 2013 12:01:04 -0500 (EST) Received: by mail-pa0-f43.google.com with SMTP id bj1so2131093pad.30 for ; Wed, 20 Nov 2013 09:01:04 -0800 (PST) Received: from psmtp.com ([74.125.245.122]) by mx.google.com with SMTP id v7si14646086pbi.278.2013.11.20.09.01.02 for ; Wed, 20 Nov 2013 09:01:03 -0800 (PST) Subject: Re: [PATCH v6 0/5] MCS Lock: MCS lock code cleanup and optimizations From: Tim Chen In-Reply-To: <20131120101957.GA19352@mudshark.cambridge.arm.com> References: <1384911446.11046.450.camel@schen9-DESK> <20131120101957.GA19352@mudshark.cambridge.arm.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 20 Nov 2013 09:00:47 -0800 Message-ID: <1384966847.11046.457.camel@schen9-DESK> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Will Deacon 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" On Wed, 2013-11-20 at 10:19 +0000, Will Deacon wrote: > 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? > I was testing it against my rwsem patches. But any workload that exercises mutex should also use this code, as this is part of mutex. Tim > 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