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sched/fair: Cleanup fair_server

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The throttle interaction made my brain hurt, make it consistently
about 0 transitions of h_nr_running.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
This commit is contained in:
Peter Zijlstra 2024-07-26 16:27:04 +02:00
parent 5f6bd380c7
commit cea5a3472a
1 changed files with 17 additions and 15 deletions
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32
kernel/sched/fair.c
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@ -5849,10 +5849,10 @@ static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
/* At this point se is NULL and we are at root level*/
sub_nr_running(rq, task_delta);
done:
/* Stop the fair server if throttling resulted in no runnable tasks */
if (rq_h_nr_running && !rq->cfs.h_nr_running)
dl_server_stop(&rq->fair_server);
done:
/*
* Note: distribution will already see us throttled via the
* throttled-list. rq->lock protects completion.
@ -5940,16 +5940,16 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
goto unthrottle_throttle;
}
/* Start the fair server if un-throttling resulted in new runnable tasks */
if (!rq_h_nr_running && rq->cfs.h_nr_running)
dl_server_start(&rq->fair_server);
/* At this point se is NULL and we are at root level*/
add_nr_running(rq, task_delta);
unthrottle_throttle:
assert_list_leaf_cfs_rq(rq);
/* Start the fair server if un-throttling resulted in new runnable tasks */
if (!rq_h_nr_running && rq->cfs.h_nr_running)
dl_server_start(&rq->fair_server);
/* Determine whether we need to wake up potentially idle CPU: */
if (rq->curr == rq->idle && rq->cfs.nr_running)
resched_curr(rq);
@ -6771,6 +6771,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
struct sched_entity *se = &p->se;
int idle_h_nr_running = task_has_idle_policy(p);
int task_new = !(flags & ENQUEUE_WAKEUP);
int rq_h_nr_running = rq->cfs.h_nr_running;
/*
* The code below (indirectly) updates schedutil which looks at
@ -6780,13 +6781,6 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
*/
util_est_enqueue(&rq->cfs, p);
if (!throttled_hierarchy(task_cfs_rq(p)) && !rq->cfs.h_nr_running) {
/* Account for idle runtime */
if (!rq->nr_running)
dl_server_update_idle_time(rq, rq->curr);
dl_server_start(&rq->fair_server);
}
/*
* If in_iowait is set, the code below may not trigger any cpufreq
* utilization updates, so do it here explicitly with the IOWAIT flag
@ -6832,6 +6826,13 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
goto enqueue_throttle;
}
if (!rq_h_nr_running && rq->cfs.h_nr_running) {
/* Account for idle runtime */
if (!rq->nr_running)
dl_server_update_idle_time(rq, rq->curr);
dl_server_start(&rq->fair_server);
}
/* At this point se is NULL and we are at root level*/
add_nr_running(rq, 1);
@ -6872,6 +6873,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
int task_sleep = flags & DEQUEUE_SLEEP;
int idle_h_nr_running = task_has_idle_policy(p);
bool was_sched_idle = sched_idle_rq(rq);
int rq_h_nr_running = rq->cfs.h_nr_running;
util_est_dequeue(&rq->cfs, p);
@ -6926,14 +6928,14 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
/* At this point se is NULL and we are at root level*/
sub_nr_running(rq, 1);
if (rq_h_nr_running && !rq->cfs.h_nr_running)
dl_server_stop(&rq->fair_server);
/* balance early to pull high priority tasks */
if (unlikely(!was_sched_idle && sched_idle_rq(rq)))
rq->next_balance = jiffies;
dequeue_throttle:
if (!throttled_hierarchy(task_cfs_rq(p)) && !rq->cfs.h_nr_running)
dl_server_stop(&rq->fair_server);
util_est_update(&rq->cfs, p, task_sleep);
hrtick_update(rq);
}