linux-kernel - [PATCH 1/5] task_struct: Add field for per-task userspace scheduler hint

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Date:   Sat, 10 Sep 2022 16:23:22 +0530
From:   K Prateek Nayak <kprateek.nayak@....com>
To:     <linux-kernel@...r.kernel.org>
CC:     <aubrey.li@...ux.intel.com>, <efault@....de>,
        <gautham.shenoy@....com>, <libo.chen@...cle.com>,
        <mgorman@...hsingularity.net>, <mingo@...nel.org>,
        <peterz@...radead.org>, <song.bao.hua@...ilicon.com>,
        <srikar@...ux.vnet.ibm.com>, <tglx@...utronix.de>,
        <valentin.schneider@....com>, <vincent.guittot@...aro.org>,
        <wuyun.abel@...edance.com>, <wyes.karny@....com>,
        <yu.c.chen@...el.com>, <yangyicong@...wei.com>
Subject: [PATCH 1/5] task_struct: Add field for per-task userspace scheduler hint

- Add a field named "hint" to store the per-task userspace scheduler
  hint set via the prctl() interface.
- Hints are inherited from parent on fork. Inherited hints can be reset
  from the same prctl() interface used to set hint to default or any
  other value.
- Hints are best effort case and scheduler doesn't make any guarantees
  of strictly adhering to it.

Signed-off-by: K Prateek Nayak <kprateek.nayak@....com>
---
 include/linux/sched.h | 1 +
 init/init_task.c      | 1 +
 2 files changed, 2 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index e7b2f8a5c711..fc953c9e956a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -769,6 +769,7 @@ struct task_struct {
 	int				wake_cpu;
 #endif
 	int				on_rq;
+	unsigned int			hint;
 
 	int				prio;
 	int				static_prio;
diff --git a/init/init_task.c b/init/init_task.c
index ff6c4b9bfe6b..f5208e6a1934 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -79,6 +79,7 @@ struct task_struct init_task
 	.static_prio	= MAX_PRIO - 20,
 	.normal_prio	= MAX_PRIO - 20,
 	.policy		= SCHED_NORMAL,
+	.hint		= 0,
 	.cpus_ptr	= &init_task.cpus_mask,
 	.user_cpus_ptr	= NULL,
 	.cpus_mask	= CPU_MASK_ALL,
-- 
2.25.1