linux-kernel - [PATCH v3 2/3] sched/core: Propagate parent task's latency requirements to the child task

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Message-Id: <20200116120230.16759-3-parth@linux.ibm.com>
Date:   Thu, 16 Jan 2020 17:32:29 +0530
From:   Parth Shah <parth@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     peterz@...radead.org, mingo@...hat.com, vincent.guittot@...aro.org,
        patrick.bellasi@...bug.net, valentin.schneider@....com,
        qais.yousef@....com, pavel@....cz, dhaval.giani@...cle.com,
        qperret@...rret.net, David.Laight@...LAB.COM, pjt@...gle.com,
        tj@...nel.org, dietmar.eggemann@....com
Subject: [PATCH v3 2/3] sched/core: Propagate parent task's latency requirements to the child task

Clone parent task's latency_nice attribute to the forked child task.

Reset the latency_nice value to default value when the child task is
set to sched_reset_on_fork.

Signed-off-by: Parth Shah <parth@...ux.ibm.com>
Reviewed-by: Qais Yousef <qais.yousef@....com>
---
 kernel/sched/core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e7b08d52db93..a7359836bf17 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2854,6 +2854,9 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
 	 */
 	p->prio = current->normal_prio;
 
+	/* Propagate the parent's latency requirements to the child as well */
+	p->latency_nice = current->latency_nice;
+
 	uclamp_fork(p);
 
 	/*
@@ -2870,6 +2873,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
 		p->prio = p->normal_prio = __normal_prio(p);
 		set_load_weight(p, false);
 
+		p->latency_nice = DEFAULT_LATENCY_NICE;
 		/*
 		 * We don't need the reset flag anymore after the fork. It has
 		 * fulfilled its duty:
-- 
2.17.2