UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

sched/rt: Prevent idle task boosting 

Idle task boosting is a nono in general. There is one
exception, when PREEMPT_RT and NOHZ is active:

The idle task calls get_next_timer_interrupt() and holds
the timer wheel base->lock on the CPU and another CPU wants
to access the timer (probably to cancel it). We can safely
ignore the boosting request, as the idle CPU runs this code
with interrupts disabled and will complete the lock
protected section without being interrupted. So there is no
real need to boost.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-755rvsosz7sdzot12a3gbha6@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Thomas Gleixner 2011-06-06 20:07:38 +02:00 committed by Ingo Molnar
parent 63b2001169
commit 1c4dd99bed
1 changed files with 19 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
kernel/sched/core.c
View File

@ -3779,6 +3779,24 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
rq = __task_rq_lock(p);
/*
* Idle task boosting is a nono in general. There is one
* exception, when PREEMPT_RT and NOHZ is active:
*
* The idle task calls get_next_timer_interrupt() and holds
* the timer wheel base->lock on the CPU and another CPU wants
* to access the timer (probably to cancel it). We can safely
* ignore the boosting request, as the idle CPU runs this code
* with interrupts disabled and will complete the lock
* protected section without being interrupted. So there is no
* real need to boost.
*/
if (unlikely(p == rq->idle)) {
WARN_ON(p != rq->curr);
WARN_ON(p->pi_blocked_on);
goto out_unlock;
}
trace_sched_pi_setprio(p, prio);
oldprio = p->prio;
prev_class = p->sched_class;
@ -3802,11 +3820,10 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0);
check_class_changed(rq, p, prev_class, oldprio);
out_unlock:
__task_rq_unlock(rq);
}
#endif
void set_user_nice(struct task_struct *p, long nice)
{
int old_prio, delta, on_rq;