On Thursday 05 April 2007 08:10, Andrew Morton wrote:
> Thanks - that'll be the CPU scheduler changes.
>
> Con has produced a patch or two which might address this but afaik we don't
> yet have a definitive fix?
>
> I believe that reverting
> sched-implement-staircase-deadline-cpu-scheduler-staircase-improvements.pat
>ch will prevent it.
I posted a definitive fix which Michal tested for me offlist. Subject was:
[PATCH] sched: implement staircase deadline cpu scheduler improvements fix
Sorry about relative noise prior to that. Akpm please pick it up.
Here again just in case.
---
Use of memset was bogus. Fix it.
Fix exiting recalc_task_prio without p->array being updated.
Microoptimisation courtesy of Dmitry Adamushko <[EMAIL PROTECTED]>
Signed-off-by: Con Kolivas <[EMAIL PROTECTED]>
---
kernel/sched.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
Index: linux-2.6.21-rc5-mm4/kernel/sched.c
===================================================================
--- linux-2.6.21-rc5-mm4.orig/kernel/sched.c 2007-04-04 12:14:29.000000000
+1000
+++ linux-2.6.21-rc5-mm4/kernel/sched.c 2007-04-04 12:49:39.000000000 +1000
@@ -683,11 +683,13 @@ static void dequeue_task(struct task_str
* The task is being queued on a fresh array so it has its entitlement
* bitmap cleared.
*/
-static inline void task_new_array(struct task_struct *p, struct rq *rq)
+static void task_new_array(struct task_struct *p, struct rq *rq,
+ struct prio_array *array)
{
bitmap_zero(p->bitmap, PRIO_RANGE);
p->rotation = rq->prio_rotation;
p->time_slice = p->quota;
+ p->array = array;
}
/* Find the first slot from the relevant prio_matrix entry */
@@ -709,6 +711,8 @@ static inline int next_entitled_slot(str
DECLARE_BITMAP(tmp, PRIO_RANGE);
int search_prio, uprio = USER_PRIO(p->static_prio);
+ if (!rq->prio_level[uprio])
+ rq->prio_level[uprio] = MAX_RT_PRIO;
/*
* Only priorities equal to the prio_level and above for their
* static_prio are acceptable, and only if it's not better than
@@ -736,11 +740,8 @@ static inline int next_entitled_slot(str
static void queue_expired(struct task_struct *p, struct rq *rq)
{
- p->array = rq->expired;
- task_new_array(p, rq);
+ task_new_array(p, rq, rq->expired);
p->prio = p->normal_prio = first_prio_slot(p);
- p->time_slice = p->quota;
- p->rotation = rq->prio_rotation;
}
#ifdef CONFIG_SMP
@@ -800,9 +801,9 @@ static void recalc_task_prio(struct task
queue_expired(p, rq);
return;
} else
- task_new_array(p, rq);
+ task_new_array(p, rq, array);
} else
- task_new_array(p, rq);
+ task_new_array(p, rq, array);
queue_prio = next_entitled_slot(p, rq);
if (queue_prio >= MAX_PRIO) {
@@ -3445,7 +3446,7 @@ EXPORT_SYMBOL(sub_preempt_count);
static inline void reset_prio_levels(struct rq *rq)
{
- memset(rq->prio_level, MAX_RT_PRIO, ARRAY_SIZE(rq->prio_level));
+ memset(rq->prio_level, 0, sizeof(int) * PRIO_RANGE);
}
/*
--
-ck
-
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