Messages in this thread Patch in this message | | | From | Tejun Heo <> | Subject | [PATCH 07/43] sched: implement try_to_wake_up_local() | Date | Fri, 26 Feb 2010 21:22:44 +0900 |
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Implement try_to_wake_up_local(). try_to_wake_up_local() is similar to try_to_wake_up() but it assumes the caller has this_rq() locked and the target task is bound to this_rq(). try_to_wake_up_local() can be called from wakeup and sleep scheduler notifiers.
Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Ingo Molnar <mingo@elte.hu> --- include/linux/sched.h | 2 + kernel/sched.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 58 insertions(+), 0 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h index 401d746..b9247e6 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2103,6 +2103,8 @@ extern void release_uids(struct user_namespace *ns); extern void do_timer(unsigned long ticks); +extern bool try_to_wake_up_local(struct task_struct *p, unsigned int state, + int wake_flags); extern int wake_up_state(struct task_struct *tsk, unsigned int state); extern int wake_up_process(struct task_struct *tsk); extern void wake_up_new_task(struct task_struct *tsk, diff --git a/kernel/sched.c b/kernel/sched.c index c371b8f..439ab59 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2438,6 +2438,10 @@ static inline void ttwu_post_activation(struct task_struct *p, struct rq *rq, rq->idle_stamp = 0; } #endif + /* + * Wake up is complete, fire wake up notifier. This allows + * try_to_wake_up_local() to be called from wake up notifiers. + */ if (success) fire_sched_notifiers(p, wakeup); } @@ -2540,6 +2544,53 @@ out: } /** + * try_to_wake_up_local - try to wake up a local task with rq lock held + * @p: the thread to be awakened + * @state: the mask of task states that can be woken + * @wake_flags: wake modifier flags (WF_*) + * + * Put @p on the run-queue if it's not alredy there. The caller must + * ensure that this_rq() is locked, @p is bound to this_rq() and @p is + * not the current task. this_rq() stays locked over invocation. + * + * This function can be called from wakeup and sleep scheduler + * notifiers. Be careful not to create deep recursion by chaining + * wakeup notifiers. + * + * Returns %true if @p was woken up, %false if it was already running + * or @state didn't match @p's state. + */ +bool try_to_wake_up_local(struct task_struct *p, unsigned int state, + int wake_flags) +{ + struct rq *rq = task_rq(p); + bool success = false; + + BUG_ON(rq != this_rq()); + BUG_ON(p == current); + lockdep_assert_held(&rq->lock); + + if (!sched_feat(SYNC_WAKEUPS)) + wake_flags &= ~WF_SYNC; + + if (!(p->state & state)) + return false; + + if (!p->se.on_rq) { + if (likely(!task_running(rq, p))) { + schedstat_inc(rq, ttwu_count); + schedstat_inc(rq, ttwu_local); + } + ttwu_activate(p, rq, wake_flags & WF_SYNC, false, true); + success = true; + } + + ttwu_post_activation(p, rq, wake_flags, success); + + return success; +} + +/** * wake_up_process - Wake up a specific process * @p: The process to be woken up. * @@ -5498,6 +5549,11 @@ need_resched_nonpreemptible: if (unlikely(signal_pending_state(prev->state, prev))) { prev->state = TASK_RUNNING; } else { + /* + * Fire sleep notifier before changing any scheduler + * state. This allows try_to_wake_up_local() to be + * called from sleep notifiers. + */ fire_sched_notifiers(prev, sleep); deactivate_task(rq, prev, 1); } -- 1.6.4.2
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