openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull scheduler fix from Ingo Molnar:
 "This contains a single fix that fixes a nohz tick stopping bug when
  mixed-poliocy SCHED_FIFO and SCHED_RR tasks are present on a runqueue"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  nohz/full, sched/rt: Fix missed tick-reenabling bug in sched_can_stop_tick()
This commit is contained in:
Linus Torvalds 2016-05-06 11:53:27 -07:00
parent 18fb92c30c 2548d546d4
commit 17d25a337b
1 changed files with 16 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
kernel/sched/core.c
View File

@ -596,17 +596,8 @@ bool sched_can_stop_tick(struct rq *rq)
return false;
/*
* FIFO realtime policy runs the highest priority task (after DEADLINE).
* Other runnable tasks are of a lower priority. The scheduler tick
* isn't needed.
*/
fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
if (fifo_nr_running)
return true;
/*
* Round-robin realtime tasks time slice with other tasks at the same
* realtime priority.
* If there are more than one RR tasks, we need the tick to effect the
* actual RR behaviour.
*/
if (rq->rt.rr_nr_running) {
if (rq->rt.rr_nr_running == 1)
@ -615,8 +606,20 @@ bool sched_can_stop_tick(struct rq *rq)
return false;
}
/* Normal multitasking need periodic preemption checks */
if (rq->cfs.nr_running > 1)
/*
* If there's no RR tasks, but FIFO tasks, we can skip the tick, no
* forced preemption between FIFO tasks.
*/
fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
if (fifo_nr_running)
return true;
/*
* If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
* if there's more than one we need the tick for involuntary
* preemption.
*/
if (rq->nr_running > 1)
return false;
return true;