linux-kernel - [PATCH v1] sched/eevdf: propagate min slice during {throttle, unthrottle}_cfs

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Message-ID: <20250714040516.10196-1-jemmywong512@gmail.com>
Date: Mon, 14 Jul 2025 12:05:16 +0800
From: Jemmy Wong <jemmywong512@...il.com>
To: Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	dtcccc@...ux.alibaba.com
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH v1] sched/eevdf: propagate min slice during {throttle, unthrottle}_cfs_rq

The min slice should be propagated through task group hierarchy during
{throttle, unthrottle}_cfs_rq similar to how normal tasks are handled in
{enqueue, dequeue}_entities.

Signed-off-by: Jemmy Wong <jemmywong512@...il.com>

---
 kernel/sched/fair.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7a14da5396fb..a0fa2df65e42 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5890,6 +5890,7 @@ static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
 	struct sched_entity *se;
 	long queued_delta, runnable_delta, idle_delta, dequeue = 1;
 	long rq_h_nr_queued = rq->cfs.h_nr_queued;
+	u64 slice = 0;

 	raw_spin_lock(&cfs_b->lock);
 	/* This will start the period timer if necessary */
@@ -5950,6 +5951,7 @@ static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
 		if (qcfs_rq->load.weight) {
 			/* Avoid re-evaluating load for this entity: */
 			se = parent_entity(se);
+			slice = cfs_rq_min_slice(qcfs_rq);
 			break;
 		}
 	}
@@ -5963,6 +5965,11 @@ static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
 		update_load_avg(qcfs_rq, se, 0);
 		se_update_runnable(se);

+		se->slice = slice;
+		if (se != qcfs_rq->curr)
+			min_vruntime_cb_propagate(&se->run_node, NULL);
+		slice = cfs_rq_min_slice(qcfs_rq);
+
 		if (cfs_rq_is_idle(group_cfs_rq(se)))
 			idle_delta = cfs_rq->h_nr_queued;

@@ -5996,6 +6003,7 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
 	struct sched_entity *se;
 	long queued_delta, runnable_delta, idle_delta;
 	long rq_h_nr_queued = rq->cfs.h_nr_queued;
+	u64 slice = 0;

 	se = cfs_rq->tg->se[cpu_of(rq)];

@@ -6041,7 +6049,13 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
 			dequeue_entity(qcfs_rq, se, flags);
 		} else if (se->on_rq)
 			break;
+
+		if (slice) {
+			se->slice = slice;
+			se->custom_slice = 1;
+		}
 		enqueue_entity(qcfs_rq, se, ENQUEUE_WAKEUP);
+		slice = cfs_rq_min_slice(qcfs_rq);

 		if (cfs_rq_is_idle(group_cfs_rq(se)))
 			idle_delta = cfs_rq->h_nr_queued;
@@ -6064,6 +6078,11 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
 		if (cfs_rq_is_idle(group_cfs_rq(se)))
 			idle_delta = cfs_rq->h_nr_queued;

+		se->slice = slice;
+		if (se != qcfs_rq->curr)
+			min_vruntime_cb_propagate(&se->run_node, NULL);
+		slice = cfs_rq_min_slice(qcfs_rq);
+
 		qcfs_rq->h_nr_queued += queued_delta;
 		qcfs_rq->h_nr_runnable += runnable_delta;
 		qcfs_rq->h_nr_idle += idle_delta;
--
2.43.0