Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753093AbaBCUzm (ORCPT ); Mon, 3 Feb 2014 15:55:42 -0500 Received: from g5t0006.atlanta.hp.com ([15.192.0.43]:3313 "EHLO g5t0006.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750750AbaBCUzk (ORCPT ); Mon, 3 Feb 2014 15:55:40 -0500 Message-ID: <1391460934.7498.49.camel@j-VirtualBox> Subject: Re: [RFC][PATCH v2 5/5] mutex: Give spinners a chance to spin_on_owner if need_resched() triggered while queued From: Jason Low To: Peter Zijlstra Cc: Ingo Molnar , Paul McKenney , Waiman Long , Linus Torvalds , Thomas Gleixner , Linux Kernel Mailing List , Rik van Riel , Andrew Morton , Davidlohr Bueso , "H. Peter Anvin" , Andi Kleen , "Chandramouleeswaran, Aswin" , "Norton, Scott J" , chegu_vinod@hp.com Date: Mon, 03 Feb 2014 12:55:34 -0800 In-Reply-To: <20140203192525.GN8874@twins.programming.kicks-ass.net> References: <20140128210753.GJ11314@laptop.programming.kicks-ass.net> <1390949495.2807.52.camel@j-VirtualBox> <20140129115142.GE9636@twins.programming.kicks-ass.net> <1391138977.6284.82.camel@j-VirtualBox> <20140131140941.GF4941@twins.programming.kicks-ass.net> <20140131200825.GS5002@laptop.programming.kicks-ass.net> <1391374883.3164.8.camel@j-VirtualBox> <20140202211230.GX5002@laptop.programming.kicks-ass.net> <1391452760.7498.26.camel@j-VirtualBox> <20140203192525.GN8874@twins.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2014-02-03 at 20:25 +0100, Peter Zijlstra wrote: > On Mon, Feb 03, 2014 at 10:39:20AM -0800, Jason Low wrote: > > > To avoid the xchg on every loop. > > > > Ah yes, we want to use xchg() on &node->next. > > > > Since the cmpxchg() is now in a loop in the unlock function, an > > additional (*lock == node) check before the cmpxchg() would also be nice > > to avoid spinning on cmpxchg() there too. > > Right, I have the below; you can find the patches this depends upon > here: > > http://programming.kicks-ass.net/sekrit/patches.tar.bz2 > > --- > Subject: locking, mutex: Cancelable MCS lock for adaptive spinning > From: Peter Zijlstra > Date: Wed, 29 Jan 2014 12:51:42 +0100 > > Since we want a task waiting for a mutex_lock() to go to sleep and > reschedule on need_resched() we must be able to abort the > mcs_spin_lock() around the adaptive spin. > > Therefore implement a cancelable mcs lock. > > XXX: anybody got a better name than m_spinlock? So I was thinking something along the lines of mcs_spin_lock_cancelable() as that's essentially what this function does. -- 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/