linux-kernel - [PATCH 03/13] sched_ext: Refactor do_enqueue

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Message-ID: <20251109183112.2412147-4-tj@kernel.org>
Date: Sun,  9 Nov 2025 08:31:02 -1000
From: Tejun Heo <tj@...nel.org>
To: David Vernet <void@...ifault.com>,
	Andrea Righi <andrea.righi@...ux.dev>,
	Changwoo Min <changwoo@...lia.com>
Cc: Dan Schatzberg <schatzberg.dan@...il.com>,
	Emil Tsalapatis <etsal@...a.com>,
	sched-ext@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 03/13] sched_ext: Refactor do_enqueue_task() local and global DSQ paths

The local and global DSQ enqueue paths in do_enqueue_task() share the same
slice refill logic. Factor out the common code into a shared enqueue label.
This makes adding new enqueue cases easier. No functional changes.

Signed-off-by: Tejun Heo <tj@...nel.org>
---
 kernel/sched/ext.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 2ce226018dbe..a29bfadde89d 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1282,6 +1282,7 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 {
 	struct scx_sched *sch = scx_root;
 	struct task_struct **ddsp_taskp;
+	struct scx_dispatch_q *dsq;
 	unsigned long qseq;
 
 	WARN_ON_ONCE(!(p->scx.flags & SCX_TASK_QUEUED));
@@ -1349,8 +1350,17 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 direct:
 	direct_dispatch(sch, p, enq_flags);
 	return;
-
+local_norefill:
+	dispatch_enqueue(sch, &rq->scx.local_dsq, p, enq_flags);
+	return;
 local:
+	dsq = &rq->scx.local_dsq;
+	goto enqueue;
+global:
+	dsq = find_global_dsq(sch, p);
+	goto enqueue;
+
+enqueue:
 	/*
 	 * For task-ordering, slice refill must be treated as implying the end
 	 * of the current slice. Otherwise, the longer @p stays on the CPU, the
@@ -1358,14 +1368,7 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 	 */
 	touch_core_sched(rq, p);
 	refill_task_slice_dfl(sch, p);
-local_norefill:
-	dispatch_enqueue(sch, &rq->scx.local_dsq, p, enq_flags);
-	return;
-
-global:
-	touch_core_sched(rq, p);	/* see the comment in local: */
-	refill_task_slice_dfl(sch, p);
-	dispatch_enqueue(sch, find_global_dsq(sch, p), p, enq_flags);
+	dispatch_enqueue(sch, dsq, p, enq_flags);
 }
 
 static bool task_runnable(const struct task_struct *p)
-- 
2.51.1