Commit 98ca645f authored Mar 02, 2020 by Qais Yousef Committed by Ingo Molnar Mar 06, 2020

sched/rt: Allow pulling unfitting task

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.

LINK: https://lore.kernel.org/lkml/20200203111451.0d1da58f@oasis.local.home/


Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fixes: 804d402f ("sched/rt: Make RT capacity-aware")
Link: https://lkml.kernel.org/r/20200302132721.8353-5-qais.yousef@arm.com

parent a1bd02e1

kernel/sched/rt.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -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;

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