Messages in this thread | | | Subject | Re: [PATCH v4 3/6] sched: Teach scheduler to understand ONRQ_MIGRATING state | From | Kirill Tkhai <> | Date | Tue, 12 Aug 2014 12:34:23 +0400 |
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В Вт, 12/08/2014 в 09:55 +0200, Peter Zijlstra пишет: > On Wed, Aug 06, 2014 at 12:06:19PM +0400, Kirill Tkhai wrote: > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -331,9 +331,13 @@ static inline struct rq *__task_rq_lock(struct task_struct *p) > > lockdep_assert_held(&p->pi_lock); > > > > for (;;) { > > + while (unlikely(task_migrating(p))) > > + cpu_relax(); > > + > > rq = task_rq(p); > > raw_spin_lock(&rq->lock); > > - if (likely(rq == task_rq(p))) > > + if (likely(rq == task_rq(p) && > > + !task_migrating(p))) > > return rq; > > raw_spin_unlock(&rq->lock); > > } > > @@ -349,10 +353,14 @@ static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags) > > struct rq *rq; > > > > for (;;) { > > + while (unlikely(task_migrating(p))) > > + cpu_relax(); > > + > > raw_spin_lock_irqsave(&p->pi_lock, *flags); > > rq = task_rq(p); > > raw_spin_lock(&rq->lock); > > - if (likely(rq == task_rq(p))) > > + if (likely(rq == task_rq(p) && > > + !task_migrating(p))) > > return rq; > > raw_spin_unlock(&rq->lock); > > raw_spin_unlock_irqrestore(&p->pi_lock, *flags); > > I know I suggested that; but I changed it like the below. The advantage > is of not having two task_migrating() tests on the likely path.
I don't have objections. Should I resend the series (also with new [4/6] log commentary)?
> --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -331,15 +331,15 @@ static inline struct rq *__task_rq_lock( > lockdep_assert_held(&p->pi_lock); > > for (;;) { > - while (unlikely(task_migrating(p))) > - cpu_relax(); > - > rq = task_rq(p); > raw_spin_lock(&rq->lock); > if (likely(rq == task_rq(p) && > !task_migrating(p))) > return rq; > raw_spin_unlock(&rq->lock); > + > + while (unlikely(task_migrating(p))) > + cpu_relax(); > } > } > > @@ -353,9 +353,6 @@ static struct rq *task_rq_lock(struct ta > struct rq *rq; > > for (;;) { > - while (unlikely(task_migrating(p))) > - cpu_relax(); > - > raw_spin_lock_irqsave(&p->pi_lock, *flags); > rq = task_rq(p); > raw_spin_lock(&rq->lock); > @@ -364,6 +361,9 @@ static struct rq *task_rq_lock(struct ta > return rq; > raw_spin_unlock(&rq->lock); > raw_spin_unlock_irqrestore(&p->pi_lock, *flags); > + > + while (unlikely(task_migrating(p))) > + cpu_relax(); > } > } >
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