On 12/02/2010 07:50 PM, Chris Wright wrote:
+void requeue_task(struct rq *rq, struct task_struct *p)
+{
+ assert_spin_locked(&rq->lock);
+
+ if (!p->se.on_rq || task_running(rq, p) || task_has_rt_policy(p))
+ return;
already checked task_running(rq, p) || task_has_rt_policy(p) w/ rq lock
held.
OK, I removed the duplicate checks.
+
+ dequeue_task(rq, p, 0);
+ enqueue_task(rq, p, 0);
seems like you could condense to save an update_rq_clock() call at least,
don't know if the info_queued, info_dequeued need to be updated
Or I can do the whole operation with the task not queued.
Not sure yet what approach I'll take...
+#ifdef CONFIG_SCHED_HRTICK
+/*
+ * Yield the CPU, giving the remainder of our time slice to task p.
+ * Typically used to hand CPU time to another thread inside the same
+ * process, eg. when p holds a resource other threads are waiting for.
+ * Giving priority to p may help get that resource released sooner.
+ */
+void yield_to(struct task_struct *p)
+{
+ unsigned long flags;
+ struct sched_entity *se =&p->se;
+ struct rq *rq;
+ struct cfs_rq *cfs_rq;
+ u64 remain = slice_remain(current);
+
+ rq = task_rq_lock(p,&flags);
+ if (task_running(rq, p) || task_has_rt_policy(p))
+ goto out;
+ cfs_rq = cfs_rq_of(se);
+ se->vruntime -= remain;
+ if (se->vruntime< cfs_rq->min_vruntime)
+ se->vruntime = cfs_rq->min_vruntime;
Should these details all be in sched_fair? Seems like the wrong layer
here. And would that condition go the other way? If new vruntime is
smaller than min, then it becomes new cfs_rq->min_vruntime?
That would be nice. Unfortunately, EXPORT_SYMBOL() does
not seem to work right from sched_fair.c, which is included
from sched.c instead of being built from the makefile!
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 5119b08..2a0a595 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -974,6 +974,25 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity
*curr, int queued)
*/
#ifdef CONFIG_SCHED_HRTICK
+u64 slice_remain(struct task_struct *p)
+{
+ unsigned long flags;
+ struct sched_entity *se =&p->se;
+ struct cfs_rq *cfs_rq;
+ struct rq *rq;
+ u64 slice, ran;
+ s64 delta;
+
+ rq = task_rq_lock(p,&flags);
+ cfs_rq = cfs_rq_of(se);
+ slice = sched_slice(cfs_rq, se);
+ ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
+ delta = slice - ran;
+ task_rq_unlock(rq,&flags);
+
+ return max(delta, 0LL);
Can delta go negative?
Good question. I don't know.
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