lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

sched: prevent wakeup over-scheduling

Browse Source 
Prevent wakeup over-scheduling.  Once a task has been preempted by a
task of the same or lower priority, it becomes ineligible for repeated
preemption by same until it has been ticked, or slept.  Instead, the
task is marked for preemption at the next tick.  Tasks of higher
priority still preempt immediately.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Mike Galbraith
2007-10-15 17:00:14 +02:00
committed by Ingo Molnar
parent ce6c131131
commit 95938a35c5
3 changed files with 15 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
kernel/sched_fair.c
View File

@@ -526,6 +526,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
update_stats_dequeue(cfs_rq, se);
if (sleep) {
se->peer_preempt = 0;
#ifdef CONFIG_SCHEDSTATS
if (entity_is_task(se)) {
struct task_struct *tsk = task_of(se);
@@ -553,8 +554,10 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
ideal_runtime = sched_slice(cfs_rq, curr);
delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
if (delta_exec > ideal_runtime)
if (delta_exec > ideal_runtime ||
(sched_feat(PREEMPT_RESTRICT) && curr->peer_preempt))
resched_task(rq_of(cfs_rq)->curr);
curr->peer_preempt = 0;
}
static void
@@ -839,8 +842,12 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
if (unlikely(se->load.weight != NICE_0_LOAD))
gran = calc_delta_fair(gran, &se->load);
if (delta > gran)
resched_task(curr);
if (delta > gran) {
int now = !sched_feat(PREEMPT_RESTRICT);
if (now || p->prio < curr->prio || !se->peer_preempt++)
resched_task(curr);
}
}
}
@@ -1034,6 +1041,7 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
check_spread(cfs_rq, curr);
__enqueue_entity(cfs_rq, se);
account_entity_enqueue(cfs_rq, se);
se->peer_preempt = 0;
resched_task(rq->curr);
}