Messages in this thread | | | Subject | Re: [PATCH 22/22] sched: Remove TASK_WAKING | From | Peter Zijlstra <> | Date | Wed, 16 Mar 2011 10:53:20 +0100 |
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On Thu, 2011-03-10 at 17:49 -0800, Frank Rowand wrote: > On 03/02/11 09:38, Peter Zijlstra wrote: > > With the new locking TASK_WAKING has become obsolete, remove it. > > > > Suggested-by: Oleg Nesterov <oleg@redhat.com> > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> > > LKML-Reference: <new-submission> > > --- > > < snip > > > > Index: linux-2.6/kernel/sched.c > > =================================================================== > > --- linux-2.6.orig/kernel/sched.c > > +++ linux-2.6/kernel/sched.c > > @@ -2175,7 +2175,7 @@ void set_task_cpu(struct task_struct *p, > > * We should never call set_task_cpu() on a blocked task, > > * ttwu() will sort out the placement. > > */ > > - WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && > > + WARN_ON_ONCE(p->state != TASK_RUNNING && > > !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE)); > > > > #ifdef CONFIG_LOCKDEP > > @@ -2613,7 +2613,7 @@ try_to_wake_up(struct task_struct *p, un > > smp_rmb(); > > > > p->sched_contributes_to_load = !!task_contributes_to_load(p); > > - p->state = TASK_WAKING; > > + p->state = TASK_RUNNING; > > > > if (p->sched_class->task_waking) > > p->sched_class->task_waking(p); > > No harm if the coded as in the patch, but an alternate suggestion > if you like it: > > The only reason left for "p->state = TASK_RUNNING;" here is when > cpu is remote. If cpu is not remote then p->state will be set by: > > ttwu_queue() > ttwu_do_activate() > ttwu_do_wakeup() > p->state = TASK_RUNNING; > > It would be more clear that setting state to TASK_RUNNING is protecting > the process until it has been removed from the wake_list by > sched_ttwu_pending() by setting p->state = TASK_RUNNING in ttwu_queue_remote(). >
Yeah, its a bit of a maze.. maybe we should just drop this and keep the slightly redundant but more clear TASK_WAKING around.
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