linux-kernel - [tip: sched/urgent] sched/eevdf: Also update slice on placement

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Message-ID: <169632975832.3135.8276089037477460761.tip-bot2@tip-bot2>
Date:   Tue, 03 Oct 2023 10:42:38 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/urgent] sched/eevdf: Also update slice on placement

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     2f2fc17bab0011430ceb6f2dc1959e7d1f981444
Gitweb:        https://git.kernel.org/tip/2f2fc17bab0011430ceb6f2dc1959e7d1f981444
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Fri, 15 Sep 2023 00:48:55 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 03 Oct 2023 12:32:29 +02:00

sched/eevdf: Also update slice on placement

Tasks that never consume their full slice would not update their slice value.
This means that tasks that are spawned before the sysctl scaling keep their
original (UP) slice length.

Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy")
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20230915124822.847197830@noisy.programming.kicks-ass.net
---
 kernel/sched/fair.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index cb22592..7d73652 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4919,10 +4919,12 @@ static inline void update_misfit_status(struct task_struct *p, struct rq *rq) {}
 static void
 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
 {
-	u64 vslice = calc_delta_fair(se->slice, se);
-	u64 vruntime = avg_vruntime(cfs_rq);
+	u64 vslice, vruntime = avg_vruntime(cfs_rq);
 	s64 lag = 0;
 
+	se->slice = sysctl_sched_base_slice;
+	vslice = calc_delta_fair(se->slice, se);
+
 	/*
 	 * Due to how V is constructed as the weighted average of entities,
 	 * adding tasks with positive lag, or removing tasks with negative lag