From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755996Ab1K1XfZ (ORCPT ); Mon, 28 Nov 2011 18:35:25 -0500 Received: from e2.ny.us.ibm.com ([32.97.182.142]:43343 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755026Ab1K1XfX (ORCPT ); Mon, 28 Nov 2011 18:35:23 -0500 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, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, patches@linaro.org, "Paul E. McKenney" , "Paul E. McKenney" Subject: [PATCH RFC tip/core/rcu 09/13] rcu: Reduce latency of rcu_prepare_for_idle() Date: Mon, 28 Nov 2011 15:33:01 -0800 Message-Id: <1322523185-456-9-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.3.2 In-Reply-To: <20111128233212.GA32279@linux.vnet.ibm.com> References: <20111128233212.GA32279@linux.vnet.ibm.com> x-cbid: 11112823-5112-0000-0000-0000028618EA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paul E. McKenney Re-enable interrupts across calls to quiescent-state functions and also across force_quiescent_state() to reduce latency. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- kernel/rcutree_plugin.h | 12 +++++++----- 1 files changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 3d84dbc..42ca5a4 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -2009,7 +2009,6 @@ int rcu_needs_cpu(int cpu) */ static void rcu_prepare_for_idle(int cpu) { - int c = 0; unsigned long flags; local_irq_save(flags); @@ -2055,27 +2054,30 @@ static void rcu_prepare_for_idle(int cpu) */ #ifdef CONFIG_TREE_PREEMPT_RCU if (per_cpu(rcu_preempt_data, cpu).nxtlist) { + local_irq_restore(flags); rcu_preempt_qs(cpu); force_quiescent_state(&rcu_preempt_state, 0); - c = c || per_cpu(rcu_preempt_data, cpu).nxtlist; + local_irq_save(flags); } #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ if (per_cpu(rcu_sched_data, cpu).nxtlist) { + local_irq_restore(flags); rcu_sched_qs(cpu); force_quiescent_state(&rcu_sched_state, 0); - c = c || per_cpu(rcu_sched_data, cpu).nxtlist; + local_irq_save(flags); } if (per_cpu(rcu_bh_data, cpu).nxtlist) { + local_irq_restore(flags); rcu_bh_qs(cpu); force_quiescent_state(&rcu_bh_state, 0); - c = c || per_cpu(rcu_bh_data, cpu).nxtlist; + local_irq_save(flags); } /* * If RCU callbacks are still pending, RCU still needs this CPU. * So try forcing the callbacks through the grace period. */ - if (c) { + if (rcu_cpu_has_callbacks(cpu)) { local_irq_restore(flags); trace_rcu_prep_idle("More callbacks"); invoke_rcu_core(); -- 1.7.3.2