From: tip-bot for Peter Zijlstra <a.p.zijlstra@chello.nl>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com,
torvalds@linux-foundation.org, a.p.zijlstra@chello.nl,
efault@gmx.de, npiggin@kernel.dk, akpm@linux-foundation.org,
tglx@linutronix.de, frank.rowand@am.sony.com, mingo@elte.hu
Subject: [tip:sched/locking] sched: Deal with non-atomic min_vruntime reads on 32bits
Date: Thu, 14 Apr 2011 08:35:34 GMT [thread overview]
Message-ID: <tip-3fe1698b7fe05aeb063564e71e40d09f28d8e80c@git.kernel.org> (raw)
In-Reply-To: <20110405152729.111378493@chello.nl>
Commit-ID: 3fe1698b7fe05aeb063564e71e40d09f28d8e80c
Gitweb: http://git.kernel.org/tip/3fe1698b7fe05aeb063564e71e40d09f28d8e80c
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Tue, 5 Apr 2011 17:23:48 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 14 Apr 2011 08:52:37 +0200
sched: Deal with non-atomic min_vruntime reads on 32bits
In order to avoid reading partial updated min_vruntime values on 32bit
implement a seqcount like solution.
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110405152729.111378493@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched.c | 3 +++
kernel/sched_fair.c | 19 +++++++++++++++++--
2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index 46f42ca..7a5eb26 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -312,6 +312,9 @@ struct cfs_rq {
u64 exec_clock;
u64 min_vruntime;
+#ifndef CONFIG_64BIT
+ u64 min_vruntime_copy;
+#endif
struct rb_root tasks_timeline;
struct rb_node *rb_leftmost;
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index ad4c414f..054cebb 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -358,6 +358,10 @@ static void update_min_vruntime(struct cfs_rq *cfs_rq)
}
cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
+#ifndef CONFIG_64BIT
+ smp_wmb();
+ cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
+#endif
}
/*
@@ -1376,10 +1380,21 @@ static void task_waking_fair(struct task_struct *p)
{
struct sched_entity *se = &p->se;
struct cfs_rq *cfs_rq = cfs_rq_of(se);
+ u64 min_vruntime;
- lockdep_assert_held(&task_rq(p)->lock);
+#ifndef CONFIG_64BIT
+ u64 min_vruntime_copy;
- se->vruntime -= cfs_rq->min_vruntime;
+ do {
+ min_vruntime_copy = cfs_rq->min_vruntime_copy;
+ smp_rmb();
+ min_vruntime = cfs_rq->min_vruntime;
+ } while (min_vruntime != min_vruntime_copy);
+#else
+ min_vruntime = cfs_rq->min_vruntime;
+#endif
+
+ se->vruntime -= min_vruntime;
}
#ifdef CONFIG_FAIR_GROUP_SCHED
next prev parent reply other threads:[~2011-04-14 8:36 UTC|newest]
Thread overview: 152+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-05 15:23 [PATCH 00/21] sched: Reduce runqueue lock contention -v6 Peter Zijlstra
2011-04-05 15:23 ` [PATCH 01/21] sched: Provide scheduler_ipi() callback in response to smp_send_reschedule() Peter Zijlstra
2011-04-13 21:15 ` Tony Luck
2011-04-13 21:38 ` Peter Zijlstra
2011-04-14 8:31 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 02/21] sched: Always provide p->on_cpu Peter Zijlstra
2011-04-14 8:31 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 03/21] mutex: Use p->on_cpu for the adaptive spin Peter Zijlstra
2011-04-14 8:32 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 04/21] sched: Change the ttwu success details Peter Zijlstra
2011-04-13 9:23 ` Peter Zijlstra
2011-04-13 10:48 ` Peter Zijlstra
2011-04-13 11:06 ` Peter Zijlstra
2011-04-13 18:39 ` Tejun Heo
2011-04-13 19:11 ` Peter Zijlstra
2011-04-14 8:32 ` [tip:sched/locking] sched: Change the ttwu() " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 05/21] sched: Clean up ttwu stats Peter Zijlstra
2011-04-14 8:33 ` [tip:sched/locking] sched: Clean up ttwu() stats tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 06/21] sched: Provide p->on_rq Peter Zijlstra
2011-04-14 8:33 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 07/21] sched: Serialize p->cpus_allowed and ttwu() using p->pi_lock Peter Zijlstra
2011-04-14 8:34 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 08/21] sched: Drop the rq argument to sched_class::select_task_rq() Peter Zijlstra
2011-04-14 8:34 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 09/21] sched: Remove rq argument to sched_class::task_waking() Peter Zijlstra
2011-04-14 8:35 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 10/21] sched: Deal with non-atomic min_vruntime reads on 32bits Peter Zijlstra
2011-04-14 8:35 ` tip-bot for Peter Zijlstra [this message]
2011-04-05 15:23 ` [PATCH 11/21] sched: Delay task_contributes_to_load() Peter Zijlstra
2011-04-14 8:35 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 12/21] sched: Also serialize ttwu_local() with p->pi_lock Peter Zijlstra
2011-04-14 8:36 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 13/21] sched: Add p->pi_lock to task_rq_lock() Peter Zijlstra
2011-04-14 8:36 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-06-01 13:58 ` Arne Jansen
2011-06-01 16:35 ` Peter Zijlstra
2011-06-01 17:20 ` Arne Jansen
2011-06-01 18:09 ` Peter Zijlstra
2011-06-01 18:44 ` Peter Zijlstra
2011-06-01 19:30 ` Arne Jansen
2011-06-01 21:09 ` Linus Torvalds
2011-06-03 9:15 ` Peter Zijlstra
2011-06-03 10:02 ` Arne Jansen
2011-06-03 10:30 ` Peter Zijlstra
2011-06-03 11:52 ` Arne Jansen
2011-06-05 8:17 ` Ingo Molnar
2011-06-05 8:53 ` Arne Jansen
2011-06-05 9:41 ` Ingo Molnar
2011-06-05 9:45 ` Ingo Molnar
2011-06-05 9:43 ` Arne Jansen
2011-06-05 9:55 ` Ingo Molnar
2011-06-05 10:22 ` Arne Jansen
2011-06-05 11:01 ` Ingo Molnar
2011-06-05 11:19 ` [debug patch] printk: Add a printk killswitch to robustify NMI watchdog messages Ingo Molnar
2011-06-05 11:36 ` Ingo Molnar
2011-06-05 11:57 ` Arne Jansen
2011-06-05 13:39 ` Ingo Molnar
2011-06-05 13:54 ` Arne Jansen
2011-06-05 14:06 ` Ingo Molnar
2011-06-05 14:45 ` Arne Jansen
2011-06-05 14:10 ` Ingo Molnar
2011-06-05 14:31 ` Arne Jansen
2011-06-05 15:13 ` Ingo Molnar
2011-06-05 15:26 ` Ingo Molnar
2011-06-05 15:32 ` Ingo Molnar
2011-06-05 16:07 ` Arne Jansen
2011-06-05 16:35 ` Arne Jansen
2011-06-05 16:50 ` Arne Jansen
2011-06-05 17:20 ` Ingo Molnar
2011-06-05 17:42 ` Arne Jansen
2011-06-05 18:59 ` Ingo Molnar
2011-06-05 19:30 ` Arne Jansen
2011-06-05 19:44 ` Ingo Molnar
2011-06-05 20:15 ` Arne Jansen
2011-06-06 6:56 ` Arne Jansen
2011-06-06 9:01 ` Peter Zijlstra
2011-06-06 9:18 ` Arne Jansen
2011-06-06 9:24 ` Peter Zijlstra
2011-06-06 9:52 ` Peter Zijlstra
2011-06-06 10:00 ` Arne Jansen
2011-06-06 10:26 ` Peter Zijlstra
2011-06-06 13:25 ` Peter Zijlstra
2011-06-06 15:04 ` Ingo Molnar
2011-06-06 15:08 ` Ingo Molnar
2011-06-06 17:44 ` Mike Galbraith
2011-06-07 5:20 ` Mike Galbraith
2011-06-06 13:10 ` Ingo Molnar
2011-06-06 13:12 ` Peter Zijlstra
2011-06-06 13:21 ` Ingo Molnar
2011-06-06 13:31 ` Peter Zijlstra
2011-06-06 7:34 ` Arne Jansen
2011-06-05 15:34 ` Arne Jansen
2011-06-06 8:38 ` Peter Zijlstra
2011-06-06 14:58 ` Ingo Molnar
2011-06-06 15:09 ` Peter Zijlstra
2011-06-06 15:47 ` Peter Zijlstra
2011-06-06 15:52 ` Ingo Molnar
2011-06-06 16:00 ` Peter Zijlstra
2011-06-06 16:08 ` Ingo Molnar
2011-06-06 16:12 ` Peter Zijlstra
2011-06-06 16:17 ` Ingo Molnar
2011-06-06 16:38 ` Arne Jansen
2011-06-06 16:45 ` Arne Jansen
2011-06-06 16:53 ` Peter Zijlstra
2011-06-06 17:07 ` Ingo Molnar
2011-06-06 17:11 ` Peter Zijlstra
2011-06-08 15:50 ` Peter Zijlstra
2011-06-08 19:17 ` Ingo Molnar
2011-06-08 19:27 ` Linus Torvalds
2011-06-08 20:32 ` Peter Zijlstra
2011-06-08 20:53 ` Linus Torvalds
2011-06-08 20:54 ` Thomas Gleixner
2011-06-08 19:45 ` Peter Zijlstra
2011-06-08 20:52 ` Ingo Molnar
2011-06-08 21:49 ` Peter Zijlstra
2011-06-08 21:57 ` Thomas Gleixner
2011-06-06 16:44 ` Peter Zijlstra
2011-06-06 16:50 ` Peter Zijlstra
2011-06-06 17:13 ` Ingo Molnar
2011-06-06 17:04 ` Peter Zijlstra
2011-06-06 17:11 ` Ingo Molnar
2011-06-06 17:57 ` Arne Jansen
2011-06-06 18:07 ` Ingo Molnar
2011-06-06 18:14 ` Arne Jansen
2011-06-06 18:19 ` Peter Zijlstra
2011-06-06 22:08 ` Ingo Molnar
2011-06-03 12:44 ` [tip:sched/locking] sched: Add p->pi_lock to task_rq_lock() Linus Torvalds
2011-06-03 13:05 ` Arne Jansen
2011-06-04 21:29 ` Linus Torvalds
2011-06-04 22:08 ` Peter Zijlstra
2011-06-04 22:50 ` Linus Torvalds
2011-06-05 6:01 ` Arne Jansen
2011-06-05 7:57 ` Mike Galbraith
2011-04-05 15:23 ` [PATCH 14/21] sched: Drop rq->lock from first part of wake_up_new_task() Peter Zijlstra
2011-04-14 8:37 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 15/21] sched: Drop rq->lock from sched_exec() Peter Zijlstra
2011-04-14 8:37 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 16/21] sched: Remove rq->lock from the first half of ttwu() Peter Zijlstra
2011-04-14 8:38 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 17/21] sched: Remove rq argument from ttwu_stat() Peter Zijlstra
2011-04-14 8:38 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 18/21] sched: Rename ttwu_post_activation Peter Zijlstra
2011-04-14 8:39 ` [tip:sched/locking] sched: Rename ttwu_post_activation() to ttwu_do_wakeup() tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 19/21] sched: Restructure ttwu some more Peter Zijlstra
2011-04-14 8:39 ` [tip:sched/locking] sched: Restructure ttwu() " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 20/21] sched: Move the second half of ttwu() to the remote cpu Peter Zijlstra
2011-04-14 8:39 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:23 ` [PATCH 21/21] sched: Remove need_migrate_task() Peter Zijlstra
2011-04-14 8:40 ` [tip:sched/locking] " tip-bot for Peter Zijlstra
2011-04-05 15:59 ` [PATCH 00/21] sched: Reduce runqueue lock contention -v6 Peter Zijlstra
2011-04-06 11:00 ` Peter Zijlstra
2011-04-27 16:54 ` Dave Kleikamp
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