linux-kernel - [PATCH 1/9] sched: Use set_next

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Message-Id: <20240813224015.614146342@infradead.org>
Date: Wed, 14 Aug 2024 00:25:49 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: mingo@...nel.org,
 tj@...nel.org,
 void@...ifault.com
Cc: peterz@...radead.org,
 juri.lelli@...hat.com,
 vincent.guittot@...aro.org,
 dietmar.eggemann@....com,
 rostedt@...dmis.org,
 bsegall@...gle.com,
 mgorman@...e.de,
 vschneid@...hat.com,
 linux-kernel@...r.kernel.org,
 joelaf@...gle.com
Subject: [PATCH 1/9] sched: Use set_next_task(.first) where required

Turns out the core_sched bits forgot to use the
set_next_task(.first=true) variant. Notably:

  pick_next_task() := pick_task() + set_next_task(.first = true)

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/sched/core.c  |    4 ++--
 kernel/sched/sched.h |    4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6010,7 +6010,7 @@ pick_next_task(struct rq *rq, struct tas
 		next = rq->core_pick;
 		if (next != prev) {
 			put_prev_task(rq, prev);
-			set_next_task(rq, next);
+			set_next_task_first(rq, next);
 		}
 
 		rq->core_pick = NULL;
@@ -6184,7 +6184,7 @@ pick_next_task(struct rq *rq, struct tas
 	}
 
 out_set_next:
-	set_next_task(rq, next);
+	set_next_task_first(rq, next);
 out:
 	if (rq->core->core_forceidle_count && next == rq->idle)
 		queue_core_balance(rq);
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2363,6 +2363,10 @@ static inline void set_next_task(struct
 	next->sched_class->set_next_task(rq, next, false);
 }
 
+static inline void set_next_task_first(struct rq *rq, struct task_struct *next)
+{
+	next->sched_class->set_next_task(rq, next, true);
+}
 
 /*
  * Helper to define a sched_class instance; each one is placed in a separate