From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932209Ab2EAAEk (ORCPT ); Mon, 30 Apr 2012 20:04:40 -0400 Received: from mail-qa0-f46.google.com ([209.85.216.46]:41691 "EHLO mail-qa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932189Ab2EAAEh (ORCPT ); Mon, 30 Apr 2012 20:04:37 -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 , Hakan Akkan , Ingo Molnar , Kevin Hilman , Max Krasnyansky , "Paul E. McKenney" , Peter Zijlstra , Stephen Hemminger , Steven Rostedt , Sven-Thorsten Dietrich , Thomas Gleixner Subject: [PATCH 30/41] sched: Update rq clock on nohz CPU before migrating tasks Date: Tue, 1 May 2012 01:55:04 +0200 Message-Id: <1335830115-14335-31-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1335830115-14335-1-git-send-email-fweisbec@gmail.com> References: <1335830115-14335-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Because the sched_class::put_prev_task() callback of rt and fair classes are referring to the rq clock to update their runtime statistics. A CPU running in tickless mode may carry a stale value. We need to update it there. 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: Hakan Akkan Cc: Ingo Molnar Cc: Kevin Hilman Cc: Max Krasnyansky Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Stephen Hemminger Cc: Steven Rostedt Cc: Sven-Thorsten Dietrich Cc: Thomas Gleixner --- kernel/sched/core.c | 6 ++++++ kernel/sched/sched.h | 6 ++++++ 2 files changed, 12 insertions(+), 0 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d24da6b..a7e611a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5166,6 +5166,12 @@ static void migrate_tasks(unsigned int dead_cpu) /* Ensure any throttled groups are reachable by pick_next_task */ unthrottle_offline_cfs_rqs(rq); + /* + * ->put_prev_task() need to have an up-to-date value + * of rq->clock[_task] + */ + update_nohz_rq_clock(rq); + for ( ; ; ) { /* * There's this thread running, bail when that's the only diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index b89f254..b463e82 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -957,6 +957,12 @@ static inline void dec_nr_running(struct rq *rq) extern void update_rq_clock(struct rq *rq); +static inline void update_nohz_rq_clock(struct rq *rq) +{ + if (cpuset_cpu_adaptive_nohz(cpu_of(rq))) + update_rq_clock(rq); +} + extern void activate_task(struct rq *rq, struct task_struct *p, int flags); extern void deactivate_task(struct rq *rq, struct task_struct *p, int flags); -- 1.7.5.4