Messages in this thread | | | Date | Sun, 02 Oct 2011 16:01:57 +0200 | From | Manfred Spraul <> | Subject | Re: [RFC][PATCH 1/3] sched: Provide delayed wakeup list |
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Hi Peter,
Do you still work on the wake_up_list() patch?
On 09/14/2011 03:30 PM, Peter Zijlstra wrote: > /* > * wake flags > */ > @@ -1255,6 +1268,8 @@ struct task_struct { > unsigned int btrace_seq; > #endif > > + struct wake_list_node wake_list; > + > unsigned int policy; > cpumask_t cpus_allowed; A global wake_list > > @@ -2143,6 +2158,35 @@ extern void wake_up_new_task(struct task > extern void sched_fork(struct task_struct *p); > extern void sched_dead(struct task_struct *p); > > +static inline void > +wake_list_add(struct wake_list_head *head, struct task_struct *p) > +{ > + struct wake_list_node *n =&p->wake_list; > + > + get_task_struct(p); > + /* > + * Atomically grab the task, if ->wake_list is !0 already it means > + * its already queued (either by us or someone else) and will get the > + * wakeup due to that. > + * > + * This cmpxchg() implies a full barrier, which pairs with the write > + * barrier implied by the wakeup in wake_up_list(). > + */ > + if (cmpxchg(&n->next, 0, n) != 0) { > + /* It was already queued, drop the extra ref and we're done. */ > + put_task_struct(p); > + return; > + } > + A task can be only once on the wake_list. > + /* > + * The head is context local, there can be no concurrency. > + */ > + n->next = head->first; > + head->first = n; > +} > + > +extern void wake_up_list(struct wake_list_head *head, unsigned int state); > + > extern void proc_caches_init(void); > extern void flush_signals(struct task_struct *); > extern void __flush_signals(struct task_struct *); > Index: linux-2.6/kernel/sched.c > =================================================================== > --- linux-2.6.orig/kernel/sched.c > +++ linux-2.6/kernel/sched.c > @@ -2916,6 +2916,25 @@ int wake_up_state(struct task_struct *p, > return try_to_wake_up(p, state, 0); > } > > +void wake_up_list(struct wake_list_head *head, unsigned int state) > +{ > + struct wake_list_node *n = head->first; > + struct task_struct *p; > + > + while (n != WAKE_LIST_TAIL) { > + p = container_of(n, struct task_struct, wake_list); > + n = n->next; > + > + p->wake_list.next = NULL; > + /* > + * wake_up_state() implies a wmb() to pair with the queueing > + * in wake_list_add() so as not to miss wakeups. > + */ > + wake_up_state(p, state); > + put_task_struct(p); > + } > +} And wake_up_list() uses state. That can't work: What if one waker wants to wake TASK_INTERRUPTIBLE and the other waker wants to wake TASK_UNINTERRUPTIBLE|TASK_INTERRUPTIBLE?
-- Manfred
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