linux-kernel - [tip: sched/core] sched/eevdf: Force propagating min_slice of cfs

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Message-ID: <173961695692.10177.11974788721404078533.tip-bot2@tip-bot2>
Date: Sat, 15 Feb 2025 10:55:56 -0000
From: "tip-bot2 for Tianchen Ding" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Tianchen Ding <dtcccc@...ux.alibaba.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/eevdf: Force propagating min_slice of cfs_rq
 when {en,de}queue tasks

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

Commit-ID:     563bc2161b94571ea425bbe2cf69fd38e24cdedf
Gitweb:        https://git.kernel.org/tip/563bc2161b94571ea425bbe2cf69fd38e24cdedf
Author:        Tianchen Ding <dtcccc@...ux.alibaba.com>
AuthorDate:    Tue, 11 Feb 2025 14:36:59 +08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 14 Feb 2025 10:32:01 +01:00

sched/eevdf: Force propagating min_slice of cfs_rq when {en,de}queue tasks

When a task is enqueued and its parent cgroup se is already on_rq, this
parent cgroup se will not be enqueued again, and hence the root->min_slice
leaves unchanged. The same issue happens when a task is dequeued and its
parent cgroup se has other runnable entities, and the parent cgroup se
will not be dequeued.

Force propagating min_slice when se doesn't need to be enqueued or
dequeued. Ensure the se hierarchy always get the latest min_slice.

Fixes: aef6987d8954 ("sched/eevdf: Propagate min_slice up the cgroup hierarchy")
Signed-off-by: Tianchen Ding <dtcccc@...ux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20250211063659.7180-1-dtcccc@linux.alibaba.com
---
 kernel/sched/fair.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1784752..9279bfb 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7002,6 +7002,8 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 		update_cfs_group(se);
 
 		se->slice = slice;
+		if (se != cfs_rq->curr)
+			min_vruntime_cb_propagate(&se->run_node, NULL);
 		slice = cfs_rq_min_slice(cfs_rq);
 
 		cfs_rq->h_nr_runnable += h_nr_runnable;
@@ -7131,6 +7133,8 @@ static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags)
 		update_cfs_group(se);
 
 		se->slice = slice;
+		if (se != cfs_rq->curr)
+			min_vruntime_cb_propagate(&se->run_node, NULL);
 		slice = cfs_rq_min_slice(cfs_rq);
 
 		cfs_rq->h_nr_runnable -= h_nr_runnable;