[PATCH v3 4/6] sched/rt: Allow pulling unfitting task

From: Qais Yousef
Date: Mon Mar 02 2020 - 08:27:48 EST


When implemented RT Capacity Awareness; the logic was done such that if
a task was running on a fitting CPU, then it was sticky and we would try
our best to keep it there.

But as Steve suggested, to adhere to the strict priority rules of RT
class; allow pulling an RT task to unfitting CPU to ensure it gets a
chance to run ASAP.

Suggested-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Fixes: 804d402fb6f6 ("sched/rt: Make RT capacity-aware")
LINK: https://lore.kernel.org/lkml/20200203111451.0d1da58f@xxxxxxxxxxxxxxxx/
Signed-off-by: Qais Yousef <qais.yousef@xxxxxxx>
---
kernel/sched/rt.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 3071c8612c03..e79a23ad4a93 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1656,8 +1656,7 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
{
if (!task_running(rq, p) &&
- cpumask_test_cpu(cpu, p->cpus_ptr) &&
- rt_task_fits_capacity(p, cpu))
+ cpumask_test_cpu(cpu, p->cpus_ptr))
return 1;

return 0;
--
2.17.1