Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755185Ab3DFQqM (ORCPT ); Sat, 6 Apr 2013 12:46:12 -0400 Received: from mail-wg0-f48.google.com ([74.125.82.48]:51280 "EHLO mail-wg0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750890Ab3DFQqK (ORCPT ); Sat, 6 Apr 2013 12:46:10 -0400 From: Frederic Weisbecker To: Ingo Molnar Cc: LKML , Frederic Weisbecker , Alessio Igor Bogani , Andrew Morton , Chris Metcalf , Christoph Lameter , Geoff Levand , Gilad Ben Yossef , Hakan Akkan , Li Zhong , Namhyung Kim , "Paul E. McKenney" , Paul Gortmaker , Peter Zijlstra , Steven Rostedt , Thomas Gleixner , Paul Turner , Mike Galbraith Subject: [PATCH 1/7] sched: Update rq clock on nohz CPU before migrating tasks Date: Sat, 6 Apr 2013 18:45:54 +0200 Message-Id: <1365266760-24725-2-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1365266760-24725-1-git-send-email-fweisbec@gmail.com> References: <1365266760-24725-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2557 Lines: 79 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: Chris Metcalf Cc: Christoph Lameter Cc: Geoff Levand Cc: Gilad Ben Yossef Cc: Hakan Akkan Cc: Ingo Molnar Cc: Li Zhong Cc: Namhyung Kim Cc: Paul E. McKenney Cc: Paul Gortmaker Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Paul Turner Cc: Mike Galbraith --- kernel/sched/core.c | 7 +++++++ kernel/sched/sched.h | 7 +++++++ 2 files changed, 14 insertions(+), 0 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e91ee58..1826e00 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4946,6 +4946,13 @@ static void migrate_tasks(unsigned int dead_cpu) */ rq->stop = NULL; + /* + * put_prev_task() and pick_next_task() sched + * class method both 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 3bd15a4..96f7333 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -5,6 +5,7 @@ #include #include #include +#include #include "cpupri.h" @@ -1115,6 +1116,12 @@ 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 (tick_nohz_extended_cpu(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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/