[PATCH v7 3/9] sched/core: Propagate parent task's latency requirements to the child task

Vincent Guittot
2022-10-28T09:35:20Z

From: Parth Shah <parth@linux.ibm.com>

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.

Also, initialize init_task.latency_nice value with DEFAULT_LATENCY_NICE
value

Signed-off-by: Parth Shah <parth@linux.ibm.com>
[rebase]
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
init/init_task.c | 1 +
kernel/sched/core.c | 1 +
2 files changed, 2 insertions(+)

diff --git a/init/init_task.c b/init/init_task.c
index ff6c4b9bfe6b..7dd71dd2d261 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -78,6 +78,7 @@ struct task_struct init_task
.prio = MAX_PRIO - 20,
.static_prio = MAX_PRIO - 20,
.normal_prio = MAX_PRIO - 20,
+ .latency_nice = DEFAULT_LATENCY_NICE,
.policy = SCHED_NORMAL,
.cpus_ptr = &init_task.cpus_mask,
.user_cpus_ptr = NULL,
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 02dc1b8e3cb6..54544353025b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4559,6 +4559,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
p->prio = p->normal_prio = p->static_prio;
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:
--
2.17.1