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authorIngo Molnar <mingo@kernel.org>2015-02-04 07:44:00 +0100
committerIngo Molnar <mingo@kernel.org>2015-02-04 07:44:00 +0100
commit4c195c8a1967ff8bee13a811518a99db04618ab7 (patch)
tree555682bd243ac56920ef7a2f3c1f3b666996c7b3 /kernel/sched
parent16b269436b7213ebc01dcfcc9dafa8535b676ccb (diff)
parent40767b0dc768060266d261b4a330164b4be53f7c (diff)
downloadop-kernel-dev-4c195c8a1967ff8bee13a811518a99db04618ab7.zip
op-kernel-dev-4c195c8a1967ff8bee13a811518a99db04618ab7.tar.gz
Merge branch 'sched/urgent' into sched/core, to merge fixes before applying new patches
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c33
-rw-r--r--kernel/sched/deadline.c3
2 files changed, 30 insertions, 6 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 54dce01..50a5352 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1816,6 +1816,10 @@ void __dl_clear_params(struct task_struct *p)
dl_se->dl_period = 0;
dl_se->flags = 0;
dl_se->dl_bw = 0;
+
+ dl_se->dl_throttled = 0;
+ dl_se->dl_new = 1;
+ dl_se->dl_yielded = 0;
}
/*
@@ -1844,7 +1848,7 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
#endif
RB_CLEAR_NODE(&p->dl.rb_node);
- hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ init_dl_task_timer(&p->dl);
__dl_clear_params(p);
INIT_LIST_HEAD(&p->rt.run_list);
@@ -2054,6 +2058,9 @@ static inline int dl_bw_cpus(int i)
* allocated bandwidth to reflect the new situation.
*
* This function is called while holding p's rq->lock.
+ *
+ * XXX we should delay bw change until the task's 0-lag point, see
+ * __setparam_dl().
*/
static int dl_overflow(struct task_struct *p, int policy,
const struct sched_attr *attr)
@@ -3263,15 +3270,31 @@ __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
{
struct sched_dl_entity *dl_se = &p->dl;
- init_dl_task_timer(dl_se);
dl_se->dl_runtime = attr->sched_runtime;
dl_se->dl_deadline = attr->sched_deadline;
dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
dl_se->flags = attr->sched_flags;
dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
- dl_se->dl_throttled = 0;
- dl_se->dl_new = 1;
- dl_se->dl_yielded = 0;
+
+ /*
+ * Changing the parameters of a task is 'tricky' and we're not doing
+ * the correct thing -- also see task_dead_dl() and switched_from_dl().
+ *
+ * What we SHOULD do is delay the bandwidth release until the 0-lag
+ * point. This would include retaining the task_struct until that time
+ * and change dl_overflow() to not immediately decrement the current
+ * amount.
+ *
+ * Instead we retain the current runtime/deadline and let the new
+ * parameters take effect after the current reservation period lapses.
+ * This is safe (albeit pessimistic) because the 0-lag point is always
+ * before the current scheduling deadline.
+ *
+ * We can still have temporary overloads because we do not delay the
+ * change in bandwidth until that time; so admission control is
+ * not on the safe side. It does however guarantee tasks will never
+ * consume more than promised.
+ */
}
/*
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index e7b2722..e0e9c29 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1094,6 +1094,7 @@ static void task_dead_dl(struct task_struct *p)
* Since we are TASK_DEAD we won't slip out of the domain!
*/
raw_spin_lock_irq(&dl_b->lock);
+ /* XXX we should retain the bw until 0-lag */
dl_b->total_bw -= p->dl.dl_bw;
raw_spin_unlock_irq(&dl_b->lock);
@@ -1613,8 +1614,8 @@ static void cancel_dl_timer(struct rq *rq, struct task_struct *p)
static void switched_from_dl(struct rq *rq, struct task_struct *p)
{
+ /* XXX we should retain the bw until 0-lag */
cancel_dl_timer(rq, p);
-
__dl_clear_params(p);
/*
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