[RFC 2/3] Propagate parent task's latency requirements to the child task

From: Parth Shah
Date: Mon Nov 25 2019 - 04:47:15 EST


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

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

Signed-off-by: Parth Shah <parth@xxxxxxxxxxxxx>
---
kernel/sched/core.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7880f4f64d0e..ea7abbf5c1bb 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2853,6 +2853,9 @@ 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_tolerance = current->latency_tolerance;
+
uclamp_fork(p);

/*
@@ -2869,6 +2872,7 @@ 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_tolerance = DEFAULT_LATENCY_TOLERANCE;
/*
* We don't need the reset flag anymore after the fork. It has
* fulfilled its duty:
--
2.17.2