[tip:sched/urgent] sched: Fix/add missing update_rq_clock() calls

tip-bot for Mike Galbraith
2009-11-12T11:34:10Z

Commit-ID: 055a00865dcfc8e61f3cbefbb879c9577bd36ae5
Gitweb: http://git.kernel.org/tip/055a00865dcfc8e61f3cbefbb879c9577bd36ae5
Author: Mike Galbraith <efault@gmx.de>
AuthorDate: Thu, 12 Nov 2009 11:07:44 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 12 Nov 2009 12:28:29 +0100

sched: Fix/add missing update_rq_clock() calls

kthread_bind(), migrate_task() and sched_fork were missing
updates, and try_to_wake_up() was updating after having already
used the stale clock.

Aside from preventing potential latency hits, there' a side
benefit in that early boot printk time stamps become monotonic.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1258020464.6491.2.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <new-submission>
---
kernel/sched.c | 17 ++++++++++++-----
1 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 3c11ae0..701eca4 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2017,6 +2017,7 @@ void kthread_bind(struct task_struct *p, unsigned int cpu)
}

spin_lock_irqsave(&rq->lock, flags);
+ update_rq_clock(rq);
set_task_cpu(p, cpu);
p->cpus_allowed = cpumask_of_cpu(cpu);
p->rt.nr_cpus_allowed = 1;
@@ -2115,6 +2116,7 @@ migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
* it is sufficient to simply update the task's cpu field.
*/
if (!p->se.on_rq && !task_running(rq, p)) {
+ update_rq_clock(rq);
set_task_cpu(p, dest_cpu);
return 0;
}
@@ -2376,14 +2378,15 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
task_rq_unlock(rq, &flags);

cpu = p->sched_class->select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
- if (cpu != orig_cpu)
+ if (cpu != orig_cpu) {
+ local_irq_save(flags);
+ rq = cpu_rq(cpu);
+ update_rq_clock(rq);
set_task_cpu(p, cpu);
-
+ local_irq_restore(flags);
+ }
rq = task_rq_lock(p, &flags);

- if (rq != orig_rq)
- update_rq_clock(rq);
-
WARN_ON(p->state != TASK_WAKING);
cpu = task_cpu(p);

@@ -2545,6 +2548,7 @@ static void __sched_fork(struct task_struct *p)
void sched_fork(struct task_struct *p, int clone_flags)
{
int cpu = get_cpu();
+ unsigned long flags;

__sched_fork(p);

@@ -2581,7 +2585,10 @@ void sched_fork(struct task_struct *p, int clone_flags)
#ifdef CONFIG_SMP
cpu = p->sched_class->select_task_rq(p, SD_BALANCE_FORK, 0);
#endif
+ local_irq_save(flags);
+ update_rq_clock(cpu_rq(cpu));
set_task_cpu(p, cpu);
+ local_irq_restore(flags);

#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
if (likely(sched_info_on()))