From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753997Ab2ITSso (ORCPT ); Thu, 20 Sep 2012 14:48:44 -0400 Received: from e5.ny.us.ibm.com ([32.97.182.145]:41907 "EHLO e5.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753633Ab2ITSsm (ORCPT ); Thu, 20 Sep 2012 14:48:42 -0400 Date: Thu, 20 Sep 2012 11:47:51 -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@efficios.com, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org Subject: [PATCH tip/core/rcu 0/23] v2 Improvements to RT response on big systems and expedited functions Message-ID: <20120920184751.GA18657@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/1.5.21 (2010-09-15) x-cbid: 12092018-5930-0000-0000-00000C4D6947 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello! This patch series contains additional improvements to latency for large systems (beyond those in 3.6), along with improvements to synchronize_rcu_expedited(). It also fixes one race introduced by the latency improvements and another that was there to start with (but made more probable by the latency improvements). These are in a single series due to conflicts that would otherwise occur. The individual patches are as follows: 1-6. Move RCU grace-period initialization and cleanup into a kthread: 1. Move RCU grace-period initialization into kthread. 2. Prevent initialization-time quiescent-state race. 3. Allow RCU grace-period initialization to be preempted. 4. Move RCU grace-period cleanup into kthread. 5. Allow RCU grace-period cleanup to be preempted. 6. Break up rcu_gp_kthread() into subfunctions. 7. Prevent offline CPUs from executing RCU core code. 8. Provide an OOM handler to allow lazy callbacks to be motivated under memory pressure. 9. Segregate rcu_state fields to improve cache locality (Courtesy of Dimitri Sivanich). 10-13. Move RCU grace-period forcing into a kthread. 10. Move quiescent-state forcing into kthread. 11. Allow RCU quiescent-state forcing to be preempted. 12. Adjust debugfs tracing for kthread-based quiescent-state forcing. 13. Prevent force_quiescent_state() memory contention. 14. Control grace-period duration from sysfs. 15. Make rcutree module parameters visible in sysfs. 16. Fix day-zero grace-period initialization/cleanup race. 17. Add random PROVE_RCU_DELAY to provoke initalization races. 18. Adjust for unconditional ->completed assignment. 19. Eliminate signed overflow in synchronize_rcu_expedited(). 20. Reduce synchronize_rcu_expedited() latency. 21. Simplify quiescent-state detection. 22. Correctly handle reconfiguring to larger leaf fanout in the case of CONFIG_RCU_FANOUT_EXACT=y. (New in this posting.) 23. Shrink RCU when there is a smaller number of CPUs than the kernel was built for (NR_CPUS < nr_cpu_ids) even when the leaf fanout did not change. (New in this posting.) Changes from v1 (https://lkml.org/lkml/2012/8/30/171): o Incorporated feedback from that posting (thank you Peter, Josh, and Lai!). This involves some serious rebasing, so the patch numbers do not match v1. o Added patches #22 and #23 above. Thanx, Paul b/Documentation/RCU/trace.txt | 43 - b/Documentation/kernel-parameters.txt | 11 b/kernel/rcutree.c | 970 ++++++++++++++++++---------------- b/kernel/rcutree.h | 28 b/kernel/rcutree_plugin.h | 131 +++- b/kernel/rcutree_trace.c | 15 6 files changed, 680 insertions(+), 518 deletions(-)