Messages in this thread | | | Date | Fri, 21 Jan 2011 20:24:12 +0800 | From | Yong Zhang <> | Subject | Re: Bug in scheduler when using rt_mutex |
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On Fri, Jan 21, 2011 at 12:08:56PM +0100, Peter Zijlstra wrote: > > That's ok, we don't and aren't supposed to care what happens while he's > > gone. But we do have to make sure that vruntime is sane either when he > > leaves, or when he comes back. Seems to me the easiest is clip when he > > leaves to cover him having slept a long time before leaving, then coming > > back on us as a runner. If he comes back as a sleeper, he'll be clipped > > again anyway, so all is well. > > > > sched_fork() should probably zero child's vruntime too, so non-fair > > children can't enter fair_class with some bogus lag they never had. > > Something like so? > > Index: linux-2.6/kernel/sched.c > =================================================================== > --- linux-2.6.orig/kernel/sched.c > +++ linux-2.6/kernel/sched.c > @@ -2624,6 +2624,8 @@ void sched_fork(struct task_struct *p, i > > if (!rt_prio(p->prio)) > p->sched_class = &fair_sched_class; > + else > + p->se.vruntime = 0;
This can be moved to __sched_fork()
> > if (p->sched_class->task_fork) > p->sched_class->task_fork(p); > Index: linux-2.6/kernel/sched_fair.c > =================================================================== > --- linux-2.6.orig/kernel/sched_fair.c > +++ linux-2.6/kernel/sched_fair.c > @@ -4086,8 +4086,14 @@ static void switched_from_fair(struct rq > * have normalized the vruntime, if it was !on_rq, then only when > * the task is sleeping will it still have non-normalized vruntime. > */ > - if (!se->on_rq && p->state != TASK_RUNNING) > + if (!se->on_rq && p->state != TASK_RUNNING) { > + /* > + * Fix up our vruntime so that the current sleep doesn't > + * cause 'unlimited' sleep bonus. > + */ > + place_entity(cfs_rq, se, 0); > se->vruntime -= cfs_rq->min_vruntime;
Now I will say yes. Though it's same to my suggestion which was rejected by myself :)
Thanks, Yong
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