From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754299Ab3KPAZo (ORCPT ); Fri, 15 Nov 2013 19:25:44 -0500 Received: from e37.co.us.ibm.com ([32.97.110.158]:57544 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753805Ab3KPAXs (ORCPT ); Fri, 15 Nov 2013 19:23:48 -0500 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, 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, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 06/16] rcu: Let the world know when RCU adjusts its geometry Date: Fri, 15 Nov 2013 16:23:28 -0800 Message-Id: <1384561418-30575-6-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1384561418-30575-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20131116002316.GA29049@linux.vnet.ibm.com> <1384561418-30575-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13111600-7164-0000-0000-0000035AF08B Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" Some RCU bugs have been specific to the layout of the rcu_node tree, but RCU will silently adjust the tree at boot time if appropriate. This obscures valuable debugging information, so print a message when this happens. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index acbfead2eb82..875f2a0f9d8d 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3378,6 +3378,8 @@ static void __init rcu_init_geometry(void) if (rcu_fanout_leaf == CONFIG_RCU_FANOUT_LEAF && nr_cpu_ids == NR_CPUS) return; + pr_info("RCU: Adjusting geometry for rcu_fanout_leaf=%d, nr_cpu_ids=%d\n", + rcu_fanout_leaf, nr_cpu_ids); /* * Compute number of nodes that can be handled an rcu_node tree -- 1.8.1.5