The patch titled
sched: implement staircase scheduler yaf fix
has been added to the -mm tree. Its filename is
sched-implement-staircase-scheduler-yaf-fix.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: sched: implement staircase scheduler yaf fix
From: Con Kolivas <kernel@xxxxxxxxxxx>
Management of time_slice sharing across fork was broken by changing
time_slice to a signed int.
first_time_slice was not being cleared anywhere near often enough.
SCHED_BATCH tasks in the current implementation should advance prio_level
and best_static_prio.
Thanks Al Boldi <a1426z@xxxxxxxxx> for making me check the fork code.
Signed-off-by: Con Kolivas <kernel@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sched.c | 50 +++++++++++++++++++++++++++++------------------
1 file changed, 31 insertions(+), 19 deletions(-)
diff -puN kernel/sched.c~sched-implement-staircase-scheduler-yaf-fix kernel/sched.c
--- a/kernel/sched.c~sched-implement-staircase-scheduler-yaf-fix
+++ a/kernel/sched.c
@@ -688,6 +688,12 @@ static void dequeue_task(struct task_str
__clear_bit(p->prio, p->array->prio_bitmap);
}
+static void reset_first_time_slice(struct task_struct *p)
+{
+ if (unlikely(p->first_time_slice))
+ p->first_time_slice = 0;
+}
+
/*
* The task is being queued on a fresh array so it has its entitlement
* bitmap cleared.
@@ -699,6 +705,7 @@ static void task_new_array(struct task_s
p->rotation = rq->prio_rotation;
p->time_slice = p->quota;
p->array = array;
+ reset_first_time_slice(p);
}
/* Find the first slot from the relevant prio_matrix entry */
@@ -767,6 +774,7 @@ static void queue_expired(struct task_st
p->prio = p->normal_prio = first_prio_slot(p);
if (p->static_prio < rq->expired->best_static_prio)
rq->expired->best_static_prio = p->static_prio;
+ reset_first_time_slice(p);
}
#ifdef CONFIG_SMP
@@ -1708,13 +1716,20 @@ void fastcall sched_fork(struct task_str
* resulting in more scheduling fairness.
*/
local_irq_disable();
- current->time_slice >>= 1;
- p->time_slice = current->time_slice;
- /*
- * The remainder of the first timeslice might be recovered by
- * the parent if the child exits early enough.
- */
- p->first_time_slice = 1;
+ if (current->time_slice > 0) {
+ current->time_slice /= 2;
+ if (current->time_slice)
+ p->time_slice = current->time_slice;
+ else
+ p->time_slice = 1;
+ /*
+ * The remainder of the first timeslice might be recovered by
+ * the parent if the child exits early enough.
+ */
+ p->first_time_slice = 1;
+ } else
+ p->time_slice = 0;
+
p->timestamp = sched_clock();
local_irq_enable();
out:
@@ -1795,7 +1810,7 @@ void fastcall sched_exit(struct task_str
parent = p->parent;
rq = task_rq_lock(parent, &flags);
- if (p->first_time_slice && task_cpu(p) == task_cpu(parent)) {
+ if (p->first_time_slice > 0 && task_cpu(p) == task_cpu(parent)) {
parent->time_slice += p->time_slice;
if (unlikely(parent->time_slice > parent->quota))
parent->time_slice = parent->quota;
@@ -3376,8 +3391,7 @@ static void task_expired_entitlement(str
struct prio_array *old_array;
int overrun, old_prio;
- if (unlikely(p->first_time_slice))
- p->first_time_slice = 0;
+ reset_first_time_slice(p);
if (rt_task(p)) {
p->time_slice = p->quota;
list_move_tail(&p->run_list, p->array->queue + p->prio);
@@ -3480,9 +3494,10 @@ static void reset_prio_levels(struct rq
*/
static inline struct task_struct *next_dynamic_task(struct rq *rq, int idx)
{
+ struct prio_array *array = rq->active;
struct task_struct *next;
struct list_head *queue;
- struct prio_array *array = rq->active;
+ int nstatic;
retry:
if (idx >= MAX_PRIO) {
@@ -3510,14 +3525,11 @@ retry:
goto retry;
}
next->rotation = rq->prio_rotation;
- if (likely(next->policy != SCHED_BATCH)) {
- int nstatic = next->static_prio;
-
- if (nstatic < array->best_static_prio)
- array->best_static_prio = nstatic;
- if (idx > rq->prio_level[USER_PRIO(nstatic)])
- rq->prio_level[USER_PRIO(nstatic)] = idx;
- }
+ nstatic = next->static_prio;
+ if (nstatic < array->best_static_prio)
+ array->best_static_prio = nstatic;
+ if (idx > rq->prio_level[USER_PRIO(nstatic)])
+ rq->prio_level[USER_PRIO(nstatic)] = idx;
return next;
}
_
Patches currently in -mm which might be from kernel@xxxxxxxxxxx are
sched-fix-idle-load-balancing-in-softirqd-context-fix.patch
sched-redundant-reschedule-when-set_user_nice-boosts-a-prio-of-a-task-from-the-expired-array.patch
sched-redundant-reschedule-when-set_user_nice-boosts-a-prio-of-a-task-from-the-expired-array-update.patch
sched-dont-renice-kernel-threads.patch
sched-remove-sleepavg-from-proc.patch
revert-sched-redundant-reschedule-when-set_user_nice-boosts-a-prio-of-a-task-from-the-expired-array.patch
sched-implement-staircase-deadline-cpu-scheduler.patch
sched-implement-staircase-deadline-cpu-scheduler-misc-fixes.patch
sched-implement-staircase-deadline-cpu-scheduler-staircase-improvements.patch
sched-implement-staircase-deadline-cpu-scheduler-improvements-fix.patch
sched-implement-staircase-deadline-cpu-scheduler-avoid-redundant-reschedule-in-set_user_nice.patch
sched-implement-staircase-deadline-cpu-scheduler-tweak.patch
sched-implement-staircase-deadline-scheduler-rework-priomatrix.patch
sched-implement-staircase-deadline-scheduler-further-improvements-1.patch
sched-implement-staircase-deadline-scheduler-timeslice-fixes.patch
sched-implement-staircase-scheduler-yaf-fix.patch
sched-increase-ksoftirqd-priority.patch
sched-remove-noninteractive-flag.patch
sched-document-sd-cpu-scheduler.patch
sched-implement-staircase-deadline-scheduler-rework-priomatrix-doc.patch
sched-consolidate-sched_clock-drift-adjustments.patch
sched-implement-staircase-deadline-scheduler-docupdate.patch
sched-add-above-background-load-function.patch
mm-implement-swap-prefetching.patch
swap-prefetch-avoid-repeating-entry.patch
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