From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id E41CF6B0093 for ; Thu, 17 Dec 2009 09:45:59 -0500 (EST) Received: from d01relay03.pok.ibm.com (d01relay03.pok.ibm.com [9.56.227.235]) by e4.ny.us.ibm.com (8.14.3/8.13.1) with ESMTP id nBHEan42016324 for ; Thu, 17 Dec 2009 09:36:49 -0500 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay03.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id nBHEjqtv119156 for ; Thu, 17 Dec 2009 09:45:52 -0500 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id nBHEjpZD011568 for ; Thu, 17 Dec 2009 09:45:52 -0500 Date: Thu, 17 Dec 2009 06:45:51 -0800 From: "Paul E. McKenney" Subject: Re: [mm][RFC][PATCH 0/11] mm accessor updates. Message-ID: <20091217144551.GA6819@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20091216120011.3eecfe79.kamezawa.hiroyu@jp.fujitsu.com> <20091216101107.GA15031@basil.fritz.box> <20091216191312.f4655dac.kamezawa.hiroyu@jp.fujitsu.com> <20091216102806.GC15031@basil.fritz.box> <20091216193109.778b881b.kamezawa.hiroyu@jp.fujitsu.com> <1261004224.21028.500.camel@laptop> <20091217084046.GA9804@basil.fritz.box> <1261039534.27920.67.camel@laptop> <20091217085430.GG9804@basil.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091217085430.GG9804@basil.fritz.box> Sender: owner-linux-mm@kvack.org To: Andi Kleen Cc: Peter Zijlstra , KAMEZAWA Hiroyuki , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , cl@linux-foundation.org, "akpm@linux-foundation.org" , "mingo@elte.hu" , minchan.kim@gmail.com List-ID: On Thu, Dec 17, 2009 at 09:54:30AM +0100, Andi Kleen wrote: > On Thu, Dec 17, 2009 at 09:45:34AM +0100, Peter Zijlstra wrote: > > On Thu, 2009-12-17 at 09:40 +0100, Andi Kleen wrote: > > > On Wed, Dec 16, 2009 at 11:57:04PM +0100, Peter Zijlstra wrote: > > > > On Wed, 2009-12-16 at 19:31 +0900, KAMEZAWA Hiroyuki wrote: > > > > > > > > > The problem of range locking is more than mmap_sem, anyway. I don't think > > > > > it's possible easily. > > > > > > > > We already have a natural range lock in the form of the split pte lock. > > > > > > > > If we make the vma lookup speculative using RCU, we can use the pte lock > > > > > > One problem is here that mmap_sem currently contains sleeps > > > and RCU doesn't work for blocking operations until a custom > > > quiescent period is defined. > > > > Right, so one thing we could do is always have preemptible rcu present > > in another RCU flavour, like > > > > rcu_read_lock_sleep() > > rcu_read_unlock_sleep() > > call_rcu_sleep() > > > > or whatever name that would be, and have PREEMPT_RCU=y only flip the > > regular rcu implementation between the sched/sleep one. > > That could work yes. OK, I have to ask... Why not just use the already-existing SRCU in this case? Thanx, Paul -- 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