Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753966AbYJ0TqK (ORCPT ); Mon, 27 Oct 2008 15:46:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752269AbYJ0Tp4 (ORCPT ); Mon, 27 Oct 2008 15:45:56 -0400 Received: from nf-out-0910.google.com ([64.233.182.185]:5501 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751889AbYJ0Tpz (ORCPT ); Mon, 27 Oct 2008 15:45:55 -0400 Message-ID: <49061AF0.8070106@colorfullife.com> Date: Mon, 27 Oct 2008 20:48:00 +0100 From: Manfred Spraul User-Agent: Thunderbird 2.0.0.16 (X11/20080723) MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: linux-kernel@vger.kernel.org, cl@linux-foundation.org, mingo@elte.hu, akpm@linux-foundation.org, dipankar@in.ibm.com, josht@linux.vnet.ibm.com, schamp@sgi.com, niv@us.ibm.com, dvhltc@us.ibm.com, ego@in.ibm.com, laijs@cn.fujitsu.com, rostedt@goodmis.org, peterz@infradead.org, penberg@cs.helsinki.fi, andi@firstfloor.org, tglx@linutronix.de Subject: Re: [PATCH, RFC] v7 scalable classic RCU implementation References: <20081010160930.GA9777@linux.vnet.ibm.com> <48F21D58.3000404@colorfullife.com> <20081012224629.GA7353@linux.vnet.ibm.com> <48F38D73.8040804@colorfullife.com> <20081015011143.GE6874@linux.vnet.ibm.com> <48F5A638.8020003@colorfullife.com> <20081015152637.GA6739@linux.vnet.ibm.com> <48FF73C7.90709@colorfullife.com> <20081022210254.GE6766@linux.vnet.ibm.com> <48FF9A0E.90205@colorfullife.com> <20081027164529.GC6783@linux.vnet.ibm.com> In-Reply-To: <20081027164529.GC6783@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1241 Lines: 31 Paul E. McKenney wrote: > Agreed. Perhaps a good change to make while introducing stall detection > to preemptable RCU -- there would then be three examples, which should > allow good generalization. > Two implementations. IMHO the current rcu-classic code should be dropped immediately when you add rcu-tree: rcu-classic is buggy, as far as I can see long-running interrupts on nohz cpus are not handled correctly. I don't think it makes sense to keep it in the kernel in parallel to rcu-tree. I would propose that rcu-tree replaces rcu-classic. I'll continue to update rcu-state, I think that it will achieve lower latency than rcu-tree [average/max time between call_rcu() and destruction callback] and it doesn't have the irq disabled loop to find the missing cpus. If I find decent benchmarks where I can quantify the advantages, then I'll propose to merge rcu-state as a third implementation in addition to rcu-tree and rcu-preempt. Paul: What do you think? -- Manfred -- 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/