From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753101AbZI0GtL (ORCPT ); Sun, 27 Sep 2009 02:49:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752276AbZI0GtL (ORCPT ); Sun, 27 Sep 2009 02:49:11 -0400 Received: from e2.ny.us.ibm.com ([32.97.182.142]:41289 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751513AbZI0GtK (ORCPT ); Sun, 27 Sep 2009 02:49:10 -0400 Date: Sat, 26 Sep 2009 23:47:53 -0700 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com Subject: [PATCH tip/core/rcu 0/2] rcu: more review feedback Message-ID: <20090927064753.GA9394@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patchset applies the last of the review comments: o Whitespace fixes, updated comments, and code movement. o Improve an existing abstraction and introduce two additional abstractions for traversing the rcu_node tree. Issues remaining: o I can force hangs given sufficient rcutorture testing in conjunction with random CPU-hotplug operations. I am working on a simpler interface between RCU and CPU hotplug that I believe will clear this up. o TREE_PREEMPT_RCU currently uses the TREE_RCU variant of synchronize_rcu_expedited, which is wrong. I am working on an expedited variant for TREE_PREEMPT_RCU, but will fall back on synchronize_rcu() for the short term if it gives me much trouble. o The IPI hyperactivity from call_rcu() noted by Nick Piggin. I believe I have identified a clean design for a fix for this. o Make RCU less dependent on IPIs for forcing grace periods (but this might be best deferred to 2.6.33). o RCU priority boosting (2.6.33!). o TINY_PREEMPT_RCU (2.6.33!). o Squeeze another 400 bytes or so out of TINY_RCU (2.6.33!).