From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754602Ab3HRBib (ORCPT ); Sat, 17 Aug 2013 21:38:31 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:43181 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753900Ab3HRBiK (ORCPT ); Sat, 17 Aug 2013 21:38:10 -0400 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, 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 02/11] rcu: Expedite during suspend and resume only on smallish systems Date: Sat, 17 Aug 2013 18:37:47 -0700 Message-Id: <1376789876-27594-2-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1376789876-27594-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20130818013735.GA27234@linux.vnet.ibm.com> <1376789876-27594-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13081801-7606-0000-0000-00000E6C105C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" Expedited grace periods are of dubious benefit on very large systems, so this commit restricts their automated use during suspend and resume to systems of 256 or fewer CPUs. Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 69e4792..6ec33dc 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -3038,7 +3038,8 @@ static int rcu_pm_notify(struct notifier_block *self, { switch (action) { case PM_HIBERNATION_PREPARE: - rcu_expedited = 1; + if (nr_cpu_ids <= 256) /* Expediting bad for large systems. */ + rcu_expedited = 1; break; case PM_POST_RESTORE: rcu_expedited = 0; -- 1.8.1.5