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sched/fair: Remove sched_feat(START_DEBIT)

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With the introduction of avg_vruntime() there is no need to use worse
approximations. Take the 0-lag point as starting point for inserting
new tasks.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124603.722361178@infradead.org
This commit is contained in:
Peter Zijlstra 2023-05-31 13:58:41 +02:00 committed by Ingo Molnar
parent af4cf40470
commit e0c2ff903c
2 changed files with 1 additions and 26 deletions
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21
kernel/sched/fair.c
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@ -906,16 +906,6 @@ static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
return slice;
}
/*
* We calculate the vruntime slice of a to-be-inserted task.
*
* vs = s/w
*/
static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
return calc_delta_fair(sched_slice(cfs_rq, se), se);
}
#include "pelt.h"
#ifdef CONFIG_SMP
@ -4862,16 +4852,7 @@ static inline bool entity_is_long_sleeper(struct sched_entity *se)
static void
place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
{
u64 vruntime = cfs_rq->min_vruntime;
/*
* The 'current' period is already promised to the current tasks,
* however the extra weight of the new task will slow them down a
* little, place the new task so that it fits in the slot that
* stays open at the end.
*/
if (initial && sched_feat(START_DEBIT))
vruntime += sched_vslice(cfs_rq, se);
u64 vruntime = avg_vruntime(cfs_rq);
/* sleeps up to a single latency don't count. */
if (!initial) {

6
kernel/sched/features.h
View file

@ -6,12 +6,6 @@
*/
SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true)
/*
* Place new tasks ahead so that they do not starve already running
* tasks
*/
SCHED_FEAT(START_DEBIT, true)
/*
* Prefer to schedule the task we woke last (assuming it failed
* wakeup-preemption), since its likely going to consume data we