From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031044Ab2CUN7v (ORCPT ); Wed, 21 Mar 2012 09:59:51 -0400 Received: from mail-we0-f174.google.com ([74.125.82.174]:61813 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030946Ab2CUN7r (ORCPT ); Wed, 21 Mar 2012 09:59:47 -0400 From: Frederic Weisbecker To: LKML , linaro-sched-sig@lists.linaro.org Cc: Frederic Weisbecker , Alessio Igor Bogani , Andrew Morton , Avi Kivity , Chris Metcalf , Christoph Lameter , Daniel Lezcano , Geoff Levand , Gilad Ben Yossef , Ingo Molnar , Max Krasnyansky , "Paul E. McKenney" , Peter Zijlstra , Stephen Hemminger , Steven Rostedt , Sven-Thorsten Dietrich , Thomas Gleixner , Zen Lin Subject: [PATCH 17/32] rcu: Restart tick if we enqueue a callback in a nohz/cpuset CPU Date: Wed, 21 Mar 2012 14:58:23 +0100 Message-Id: <1332338318-5958-19-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1332338318-5958-1-git-send-email-fweisbec@gmail.com> References: <1332338318-5958-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If we enqueue an rcu callback, we need the CPU tick to stay alive until we take care of those by completing the appropriate grace period. Thus, when we call_rcu(), send a self IPI that checks rcu_needs_cpu() so that we restore a periodic tick behaviour that can take care of everything. Signed-off-by: Frederic Weisbecker Cc: Alessio Igor Bogani Cc: Andrew Morton Cc: Avi Kivity Cc: Chris Metcalf Cc: Christoph Lameter Cc: Daniel Lezcano Cc: Geoff Levand Cc: Gilad Ben Yossef Cc: Ingo Molnar Cc: Max Krasnyansky Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Stephen Hemminger Cc: Steven Rostedt Cc: Sven-Thorsten Dietrich Cc: Thomas Gleixner Cc: Zen Lin --- kernel/rcutree.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 3fffc26..b8d300c 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1749,6 +1749,13 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), else trace_rcu_callback(rsp->name, head, rdp->qlen); + /* Restart the timer if needed to handle the callbacks */ + if (cpuset_adaptive_nohz()) { + /* Make updates on nxtlist visible to self IPI */ + barrier(); + smp_cpuset_update_nohz(smp_processor_id()); + } + /* If interrupts were disabled, don't dive into RCU core. */ if (irqs_disabled_flags(flags)) { local_irq_restore(flags); -- 1.7.5.4