| Date | Wed, 31 May 2023 13:58:41 +0200 | From | Peter Zijlstra <> | Subject | [PATCH 02/15] sched/fair: Remove 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> --- kernel/sched/fair.c | 21 +-------------------- kernel/sched/features.h | 6 ------ 2 files changed, 1 insertion(+), 26 deletions(-)
--- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -906,16 +906,6 @@ static u64 sched_slice(struct cfs_rq *cf 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_sleepe 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) { --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -7,12 +7,6 @@ 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 * touched, increases cache locality.
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