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Message-Id: <20240813224016.158454756@infradead.org>
Date: Wed, 14 Aug 2024 00:25:54 +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 6/9] sched: Combine the last put_prev_task() and the first set_next_task()
Ensure the last put_prev_task() and the first set_next_task() always
go together.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
kernel/sched/core.c | 17 ++++-------------
kernel/sched/fair.c | 3 +--
kernel/sched/sched.h | 10 +++++++++-
3 files changed, 14 insertions(+), 16 deletions(-)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5894,8 +5894,7 @@ __pick_next_task(struct rq *rq, struct t
/* Assume the next prioritized class is idle_sched_class */
if (!p) {
p = pick_task_idle(rq);
- put_prev_task(rq, prev);
- set_next_task_first(rq, p);
+ put_prev_set_next_task(rq, prev, p);
}
/*
@@ -5926,8 +5925,7 @@ __pick_next_task(struct rq *rq, struct t
} else {
p = class->pick_task(rq);
if (p) {
- put_prev_task(rq, prev);
- set_next_task_first(rq, p);
+ put_prev_set_next_task(rq, prev, p);
return p;
}
}
@@ -6016,13 +6014,8 @@ pick_next_task(struct rq *rq, struct tas
WRITE_ONCE(rq->core_sched_seq, rq->core->core_pick_seq);
next = rq->core_pick;
- if (next != prev) {
- put_prev_task(rq, prev);
- set_next_task_first(rq, next);
- }
-
rq->core_pick = NULL;
- goto out;
+ goto out_set_next;
}
prev_balance(rq, prev, rf);
@@ -6192,9 +6185,7 @@ pick_next_task(struct rq *rq, struct tas
}
out_set_next:
- put_prev_task(rq, prev);
- set_next_task_first(rq, next);
-out:
+ put_prev_set_next_task(rq, prev, next);
if (rq->core->core_forceidle_count && next == rq->idle)
queue_core_balance(rq);
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8817,8 +8817,7 @@ pick_next_task_fair(struct rq *rq, struc
simple:
#endif
- put_prev_task(rq, prev);
- set_next_task_fair(rq, p, true);
+ put_prev_set_next_task(rq, prev, p);
return p;
idle:
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2370,8 +2370,16 @@ 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)
+static inline void put_prev_set_next_task(struct rq *rq,
+ struct task_struct *prev,
+ struct task_struct *next)
{
+ WARN_ON_ONCE(rq->curr != prev);
+
+ if (next == prev)
+ return;
+
+ prev->sched_class->put_prev_task(rq, prev);
next->sched_class->set_next_task(rq, next, true);
}
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