From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932334AbVHKSFH (ORCPT ); Thu, 11 Aug 2005 14:05:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932339AbVHKSFG (ORCPT ); Thu, 11 Aug 2005 14:05:06 -0400 Received: from e1.ny.us.ibm.com ([32.97.182.141]:51623 "EHLO e1.ny.us.ibm.com") by vger.kernel.org with ESMTP id S932334AbVHKSFF (ORCPT ); Thu, 11 Aug 2005 14:05:05 -0400 Date: Thu, 11 Aug 2005 23:30:44 +0530 From: Dipankar Sarma To: Christoph Hellwig , "Paul E. McKenney" , linux-kernel@vger.kernel.org, mingo@elte.hu, rusty@au1.ibm.com, bmark@us.ibm.com Subject: Re: [RFC,PATCH] Use RCU to protect tasklist for unicast signals Message-ID: <20050811180044.GD4546@in.ibm.com> Reply-To: dipankar@in.ibm.com References: <20050810171145.GA1945@us.ibm.com> <20050811171451.GA5108@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050811171451.GA5108@infradead.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 11, 2005 at 06:14:51PM +0100, Christoph Hellwig wrote: > On Wed, Aug 10, 2005 at 10:11:45AM -0700, Paul E. McKenney wrote: > > Hello! > > > > This patch is an experiment in use of RCU for individual code paths that > > read-acquire the tasklist lock, in this case, unicast signal delivery. > > It passes five kernbenches on 4-CPU x86, but obviously needs much more > > testing before it is considered for serious use, let alone inclusion. > > I think we should switch over tasklist_lock to RCU completely instead of > adding suck hacks. I've started lots of preparation work to get rid of > tasklist_lock users outside of kernel/, especialy getting rid of any > use in modules. That would be really helpful, specially the ones in drivers/char/tty*.c :) When I worked on this last (a year or so ago), it seemed that I would need to put a number of additional structures under RCU control. It would be better to gradually move it towards RCU rather than trying make all the readers lock-free. Thanks Dipankar