p->sched_class->prio_changed(rq, p, oldprio, running);
}
-/**
- * kthread_bind - bind a just-created kthread to a cpu.
- * @p: thread created by kthread_create().
- * @cpu: cpu (might not be online, must be possible) for @k to run on.
- *
- * Description: This function is equivalent to set_cpus_allowed(),
- * except that @cpu doesn't need to be online, and the thread must be
- * stopped (i.e., just returned from kthread_create()).
- *
- * Function lives here instead of kthread.c because it messes with
- * scheduler internals which require locking.
- */
-void kthread_bind(struct task_struct *p, unsigned int cpu)
-{
- struct rq *rq = cpu_rq(cpu);
- unsigned long flags;
-
- /* Must have done schedule() in kthread() before we set_task_cpu */
- if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
- WARN_ON(1);
- return;
- }
-
- raw_spin_lock_irqsave(&rq->lock, flags);
- update_rq_clock(rq);
- set_task_cpu(p, cpu);
- p->cpus_allowed = cpumask_of_cpu(cpu);
- p->rt.nr_cpus_allowed = 1;
- p->flags |= PF_THREAD_BOUND;
- raw_spin_unlock_irqrestore(&rq->lock, flags);
-}
-EXPORT_SYMBOL(kthread_bind);
-
#ifdef CONFIG_SMP
/*
* Is this task likely cache-hot:
{
s64 delta;
+ if (p->sched_class != &fair_sched_class)
+ return 0;
+
/*
* Buddy candidates are cache hot:
*/
&p->se == cfs_rq_of(&p->se)->last))
return 1;
- if (p->sched_class != &fair_sched_class)
- return 0;
-
if (sysctl_sched_migration_cost == -1)
return 1;
if (sysctl_sched_migration_cost == 0)
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
{
int old_cpu = task_cpu(p);
- struct cfs_rq *old_cfsrq = task_cfs_rq(p),
- *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu);
+
+#ifdef CONFIG_SCHED_DEBUG
+ /*
+ * We should never call set_task_cpu() on a blocked task,
+ * ttwu() will sort out the placement.
+ */
+ WARN_ON(p->state != TASK_RUNNING && p->state != TASK_WAKING);
+#endif
trace_sched_migrate_task(p, new_cpu);
perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS,
1, 1, NULL, 0);
}
- p->se.vruntime -= old_cfsrq->min_vruntime -
- new_cfsrq->min_vruntime;
__set_task_cpu(p, new_cpu);
}
/*
* If the task is not on a runqueue (and not running), then
- * it is sufficient to simply update the task's cpu field.
+ * the next wake-up will properly place the task.
*/
- if (!p->se.on_rq && !task_running(rq, p)) {
- update_rq_clock(rq);
- set_task_cpu(p, dest_cpu);
+ if (!p->se.on_rq && !task_running(rq, p))
return 0;
- }
init_completion(&req->done);
req->task = p;
}
#ifdef CONFIG_SMP
+static int select_fallback_rq(int cpu, struct task_struct *p)
+{
+ int dest_cpu;
+ const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu));
+
+ /* Look for allowed, online CPU in same node. */
+ for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
+ if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
+ return dest_cpu;
+
+ /* Any allowed, online CPU? */
+ dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
+ if (dest_cpu < nr_cpu_ids)
+ return dest_cpu;
+
+ /* No more Mr. Nice Guy. */
+ if (dest_cpu >= nr_cpu_ids) {
+ rcu_read_lock();
+ cpuset_cpus_allowed_locked(p, &p->cpus_allowed);
+ rcu_read_unlock();
+ dest_cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed);
+
+ /*
+ * Don't tell them about moving exiting tasks or
+ * kernel threads (both mm NULL), since they never
+ * leave kernel.
+ */
+ if (p->mm && printk_ratelimit()) {
+ printk(KERN_INFO "process %d (%s) no "
+ "longer affine to cpu%d\n",
+ task_pid_nr(p), p->comm, cpu);
+ }
+ }
+
+ return dest_cpu;
+}
+
+/*
+ * Called from:
+ *
+ * - fork, @p is stable because it isn't on the tasklist yet
+ *
+ * - exec, @p is unstable, retry loop
+ *
+ * - wake-up, we serialize ->cpus_allowed against TASK_WAKING so
+ * we should be good.
+ */
static inline
int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
{
- return p->sched_class->select_task_rq(p, sd_flags, wake_flags);
+ int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags);
+
+ /*
+ * In order not to call set_task_cpu() on a blocking task we need
+ * to rely on ttwu() to place the task on a valid ->cpus_allowed
+ * cpu.
+ *
+ * Since this is common to all placement strategies, this lives here.
+ *
+ * [ this allows ->select_task() to simply return task_cpu(p) and
+ * not worry about this generic constraint ]
+ */
+ if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) ||
+ !cpu_active(cpu)))
+ cpu = select_fallback_rq(task_cpu(p), p);
+
+ return cpu;
}
#endif
if (task_contributes_to_load(p))
rq->nr_uninterruptible--;
p->state = TASK_WAKING;
+
+ if (p->sched_class->task_waking)
+ p->sched_class->task_waking(rq, p);
+
__task_rq_unlock(rq);
cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
p->state = TASK_RUNNING;
#ifdef CONFIG_SMP
- if (p->sched_class->task_wake_up)
- p->sched_class->task_wake_up(rq, p);
+ if (p->sched_class->task_woken)
+ p->sched_class->task_woken(rq, p);
if (unlikely(rq->idle_stamp)) {
u64 delta = rq->clock - rq->idle_stamp;
#ifdef CONFIG_PREEMPT_NOTIFIERS
INIT_HLIST_HEAD(&p->preempt_notifiers);
#endif
-
- /*
- * We mark the process as running here, but have not actually
- * inserted it onto the runqueue yet. This guarantees that
- * nobody will actually run it, and a signal or other external
- * event cannot wake it up and insert it on the runqueue either.
- */
- p->state = TASK_RUNNING;
}
/*
int cpu = get_cpu();
__sched_fork(p);
+ /*
+ * We mark the process as waking here. This guarantees that
+ * nobody will actually run it, and a signal or other external
+ * event cannot wake it up and insert it on the runqueue either.
+ */
+ p->state = TASK_WAKING;
/*
* Revert to default priority/policy on fork if requested.
struct rq *rq;
rq = task_rq_lock(p, &flags);
- BUG_ON(p->state != TASK_RUNNING);
+ BUG_ON(p->state != TASK_WAKING);
+ p->state = TASK_RUNNING;
update_rq_clock(rq);
activate_task(rq, p, 0);
trace_sched_wakeup_new(rq, p, 1);
check_preempt_curr(rq, p, WF_FORK);
#ifdef CONFIG_SMP
- if (p->sched_class->task_wake_up)
- p->sched_class->task_wake_up(rq, p);
+ if (p->sched_class->task_woken)
+ p->sched_class->task_woken(rq, p);
#endif
task_rq_unlock(rq, &flags);
}
}
/*
- * If dest_cpu is allowed for this process, migrate the task to it.
- * This is accomplished by forcing the cpu_allowed mask to only
- * allow dest_cpu, which will force the cpu onto dest_cpu. Then
- * the cpu_allowed mask is restored.
+ * sched_exec - execve() is a valuable balancing opportunity, because at
+ * this point the task has the smallest effective memory and cache footprint.
*/
-static void sched_migrate_task(struct task_struct *p, int dest_cpu)
+void sched_exec(void)
{
+ struct task_struct *p = current;
struct migration_req req;
+ int dest_cpu, this_cpu;
unsigned long flags;
struct rq *rq;
+again:
+ this_cpu = get_cpu();
+ dest_cpu = select_task_rq(p, SD_BALANCE_EXEC, 0);
+ if (dest_cpu == this_cpu) {
+ put_cpu();
+ return;
+ }
+
rq = task_rq_lock(p, &flags);
+ put_cpu();
+
+ /*
+ * select_task_rq() can race against ->cpus_allowed
+ */
if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed)
- || unlikely(!cpu_active(dest_cpu)))
- goto out;
+ || unlikely(!cpu_active(dest_cpu))) {
+ task_rq_unlock(rq, &flags);
+ goto again;
+ }
/* force the process onto the specified CPU */
if (migrate_task(p, dest_cpu, &req)) {
return;
}
-out:
task_rq_unlock(rq, &flags);
}
-/*
- * sched_exec - execve() is a valuable balancing opportunity, because at
- * this point the task has the smallest effective memory and cache footprint.
- */
-void sched_exec(void)
-{
- int new_cpu, this_cpu = get_cpu();
- new_cpu = select_task_rq(current, SD_BALANCE_EXEC, 0);
- put_cpu();
- if (new_cpu != this_cpu)
- sched_migrate_task(current, new_cpu);
-}
-
/*
* pull_task - move a task from a remote runqueue to the local runqueue.
* Both runqueues must be locked.
raw_spin_lock_irqsave(&rq->lock, flags);
__sched_fork(idle);
+ idle->state = TASK_RUNNING;
idle->se.exec_start = sched_clock();
cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu));
struct rq *rq;
int ret = 0;
+ /*
+ * Since we rely on wake-ups to migrate sleeping tasks, don't change
+ * the ->cpus_allowed mask from under waking tasks, which would be
+ * possible when we change rq->lock in ttwu(), so synchronize against
+ * TASK_WAKING to avoid that.
+ */
+again:
+ while (p->state == TASK_WAKING)
+ cpu_relax();
+
rq = task_rq_lock(p, &flags);
+
+ if (p->state == TASK_WAKING) {
+ task_rq_unlock(rq, &flags);
+ goto again;
+ }
+
if (!cpumask_intersects(new_mask, cpu_active_mask)) {
ret = -EINVAL;
goto out;
static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
{
struct rq *rq_dest, *rq_src;
- int ret = 0, on_rq;
+ int ret = 0;
if (unlikely(!cpu_active(dest_cpu)))
return ret;
if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
goto fail;
- on_rq = p->se.on_rq;
- if (on_rq)
+ /*
+ * If we're not on a rq, the next wake-up will ensure we're
+ * placed properly.
+ */
+ if (p->se.on_rq) {
deactivate_task(rq_src, p, 0);
-
- set_task_cpu(p, dest_cpu);
- if (on_rq) {
+ set_task_cpu(p, dest_cpu);
activate_task(rq_dest, p, 0);
check_preempt_curr(rq_dest, p, 0);
}
static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
{
int dest_cpu;
- const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(dead_cpu));
again:
- /* Look for allowed, online CPU in same node. */
- for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
- if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
- goto move;
-
- /* Any allowed, online CPU? */
- dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
- if (dest_cpu < nr_cpu_ids)
- goto move;
-
- /* No more Mr. Nice Guy. */
- if (dest_cpu >= nr_cpu_ids) {
- cpuset_cpus_allowed_locked(p, &p->cpus_allowed);
- dest_cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed);
-
- /*
- * Don't tell them about moving exiting tasks or
- * kernel threads (both mm NULL), since they never
- * leave kernel.
- */
- if (p->mm && printk_ratelimit()) {
- pr_info("process %d (%s) no longer affine to cpu%d\n",
- task_pid_nr(p), p->comm, dead_cpu);
- }
- }
+ dest_cpu = select_fallback_rq(dead_cpu, p);
-move:
/* It can have affinity changed while we were choosing. */
if (unlikely(!__migrate_task_irq(p, dead_cpu, dest_cpu)))
goto again;
#ifdef CONFIG_FAIR_GROUP_SCHED
if (tsk->sched_class->moved_group)
- tsk->sched_class->moved_group(tsk);
+ tsk->sched_class->moved_group(tsk, on_rq);
#endif
if (unlikely(running))
projects / deliverable / linux.git / blobdiff