linux-kernel - [PATCH 1/2] sched: Provide sched_set

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Message-ID: <20241114210649.71377-1-flo@geekplace.eu>
Date: Thu, 14 Nov 2024 22:06:47 +0100
From: Florian Schmaus <flo@...kplace.eu>
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>
Cc: Florian Schmaus <flo@...kplace.eu>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] sched: Provide sched_set_batch()

This function allows kernel threads created by modules to run under
SCHED_BATCH. Its usage may be a good option if the kernel thread is
not sensitive to scheduling latency; for example bcachefs' rebalancing
thread.

Signed-off-by: Florian Schmaus <flo@...kplace.eu>
---
 include/linux/sched.h   |  1 +
 kernel/sched/syscalls.c | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index bb343136ddd0..100e6923fe39 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1862,6 +1862,7 @@ extern int sched_setscheduler_nocheck(struct task_struct *, int, const struct sc
 extern void sched_set_fifo(struct task_struct *p);
 extern void sched_set_fifo_low(struct task_struct *p);
 extern void sched_set_normal(struct task_struct *p, int nice);
+extern void sched_set_batch(struct task_struct *p, int nice);
 extern int sched_setattr(struct task_struct *, const struct sched_attr *);
 extern int sched_setattr_nocheck(struct task_struct *, const struct sched_attr *);
 extern struct task_struct *idle_task(int cpu);
diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c
index 24f9f90b6574..d272c0e0c508 100644
--- a/kernel/sched/syscalls.c
+++ b/kernel/sched/syscalls.c
@@ -880,6 +880,16 @@ void sched_set_normal(struct task_struct *p, int nice)
 }
 EXPORT_SYMBOL_GPL(sched_set_normal);
 
+void sched_set_batch(struct task_struct *p, int nice)
+{
+	struct sched_attr attr = {
+		.sched_policy = SCHED_BATCH,
+		.sched_nice = nice,
+	};
+	WARN_ON_ONCE(sched_setattr_nocheck(p, &attr) != 0);
+}
+EXPORT_SYMBOL_GPL(sched_set_batch);
+
 static int
 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
 {
-- 
2.45.2