From e0c2ff903c320d3fd3c2c604dc401b3b7c0a1d13 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 31 May 2023 13:58:41 +0200 Subject: [PATCH] sched/fair: Remove sched_feat(START_DEBIT) 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) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230531124603.722361178@infradead.org --- kernel/sched/fair.c | 21 +-------------------- kernel/sched/features.h | 6 ------ 2 files changed, 1 insertion(+), 26 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index bb5460682ae2e..fc43482c13e99 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -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) { diff --git a/kernel/sched/features.h b/kernel/sched/features.h index ee7f23c76bd33..fa828b36533df 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -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