diff options
| -rw-r--r-- | include/linux/sched.h | 2 | ||||
| -rw-r--r-- | kernel/sched.c | 85 | ||||
| -rw-r--r-- | kernel/sched_fair.c | 20 |
3 files changed, 107 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 4e9fad271c3..c88b3bfbd09 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1058,6 +1058,7 @@ struct sched_class { void (*enqueue_task) (struct rq *rq, struct task_struct *p, int flags); void (*dequeue_task) (struct rq *rq, struct task_struct *p, int flags); void (*yield_task) (struct rq *rq); + bool (*yield_to_task) (struct rq *rq, struct task_struct *p, bool preempt); void (*check_preempt_curr) (struct rq *rq, struct task_struct *p, int flags); @@ -1972,6 +1973,7 @@ static inline int rt_mutex_getprio(struct task_struct *p) # define rt_mutex_adjust_pi(p) do { } while (0) #endif +extern bool yield_to(struct task_struct *p, bool preempt); extern void set_user_nice(struct task_struct *p, long nice); extern int task_prio(const struct task_struct *p); extern int task_nice(const struct task_struct *p); diff --git a/kernel/sched.c b/kernel/sched.c index ae5e1a19b9d..2effcb71a47 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1686,6 +1686,39 @@ static void double_rq_unlock(struct rq *rq1, struct rq *rq2) __release(rq2->lock); } +#else /* CONFIG_SMP */ + +/* + * double_rq_lock - safely lock two runqueues + * + * Note this does not disable interrupts like task_rq_lock, + * you need to do so manually before calling. + */ +static void double_rq_lock(struct rq *rq1, struct rq *rq2) + __acquires(rq1->lock) + __acquires(rq2->lock) +{ + BUG_ON(!irqs_disabled()); + BUG_ON(rq1 != rq2); + raw_spin_lock(&rq1->lock); + __acquire(rq2->lock); /* Fake it out ;) */ +} + +/* + * double_rq_unlock - safely unlock two runqueues + * + * Note this does not restore interrupts like task_rq_unlock, + * you need to do so manually after calling. + */ +static void double_rq_unlock(struct rq *rq1, struct rq *rq2) + __releases(rq1->lock) + __releases(rq2->lock) +{ + BUG_ON(rq1 != rq2); + raw_spin_unlock(&rq1->lock); + __release(rq2->lock); +} + #endif static void calc_load_account_idle(struct rq *this_rq); @@ -5448,6 +5481,58 @@ void __sched yield(void) } EXPORT_SYMBOL(yield); +/** + * yield_to - yield the current processor to another thread in + * your thread group, or accelerate that thread toward the + * processor it's on. + * + * It's the caller's job to ensure that the target task struct + * can't go away on us before we can do any checks. + * + * Returns true if we indeed boosted the target task. + */ +bool __sched yield_to(struct task_struct *p, bool preempt) +{ + struct task_struct *curr = current; + struct rq *rq, *p_rq; + unsigned long flags; + bool yielded = 0; + + local_irq_save(flags); + rq = this_rq(); + +again: + p_rq = task_rq(p); + double_rq_lock(rq, p_rq); + while (task_rq(p) != p_rq) { + double_rq_unlock(rq, p_rq); + goto again; + } + + if (!curr->sched_class->yield_to_task) + goto out; + + if (curr->sched_class != p->sched_class) + goto out; + + if (task_running(p_rq, p) || p->state) + goto out; + + yielded = curr->sched_class->yield_to_task(rq, p, preempt); + if (yielded) + schedstat_inc(rq, yld_count); + +out: + double_rq_unlock(rq, p_rq); + local_irq_restore(flags); + + if (yielded) + schedule(); + + return yielded; +} +EXPORT_SYMBOL_GPL(yield_to); + /* * This task is about to go to sleep on IO. Increment rq->nr_iowait so * that process accounting knows that this is a task in IO wait state. diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index c0fbeb99283..02702469404 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1975,6 +1975,25 @@ static void yield_task_fair(struct rq *rq) set_skip_buddy(se); } +static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt) +{ + struct sched_entity *se = &p->se; + + if (!se->on_rq) + return false; + + /* Tell the scheduler that we'd really like pse to run next. */ + set_next_buddy(se); + + /* Make p's CPU reschedule; pick_next_entity takes care of fairness. */ + if (preempt) + resched_task(rq->curr); + + yield_task_fair(rq); + + return true; +} + #ifdef CONFIG_SMP /************************************************** * Fair scheduling class load-balancing methods: @@ -4243,6 +4262,7 @@ static const struct sched_class fair_sched_class = { .enqueue_task = enqueue_task_fair, .dequeue_task = dequeue_task_fair, .yield_task = yield_task_fair, + .yield_to_task = yield_to_task_fair, .check_preempt_curr = check_preempt_wakeup, |