From: Qais Yousef <qais.yousef@arm.com>
To: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Pavan Kondeti <pkondeti@codeaurora.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
linux-kernel@vger.kernel.org, Qais Yousef <qais.yousef@arm.com>
Subject: [PATCH 2/3] sched/rt: allow pulling unfitting task
Date: Fri, 14 Feb 2020 16:39:48 +0000 [thread overview]
Message-ID: <20200214163949.27850-3-qais.yousef@arm.com> (raw)
In-Reply-To: <20200214163949.27850-1-qais.yousef@arm.com>
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. When doing so, mark the queue as overloaded to give
the system a chance to push the task to a better fitting CPU when a
chance arises.
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
---
kernel/sched/rt.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 4043abe45459..0c8bac134d3a 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1646,10 +1646,20 @@ 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))
+ if (!task_running(rq, p) && cpumask_test_cpu(cpu, p->cpus_ptr)) {
+
+ /*
+ * If the CPU doesn't fit the task, allow pulling but mark the
+ * rq as overloaded so that we can push it again to a more
+ * suitable CPU ASAP.
+ */
+ if (!rt_task_fits_capacity(p, cpu)) {
+ rt_set_overload(rq);
+ rq->rt.overloaded = 1;
+ }
+
return 1;
+ }
return 0;
}
--
2.17.1
next prev parent reply other threads:[~2020-02-14 16:40 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 16:39 [PATCH 0/3] RT Capacity Awareness Improvements Qais Yousef
2020-02-14 16:39 ` [PATCH 1/3] sched/rt: cpupri_find: implement fallback mechanism for !fit case Qais Yousef
2020-02-17 17:07 ` Valentin Schneider
2020-02-17 23:34 ` Qais Yousef
2020-02-18 10:01 ` Valentin Schneider
2020-02-17 19:09 ` Dietmar Eggemann
2020-02-17 23:45 ` Qais Yousef
2020-02-18 9:53 ` Dietmar Eggemann
2020-02-18 17:28 ` Qais Yousef
2020-02-18 16:46 ` Steven Rostedt
2020-02-18 17:27 ` Qais Yousef
2020-02-18 18:03 ` Steven Rostedt
2020-02-18 18:52 ` Qais Yousef
2020-02-14 16:39 ` Qais Yousef [this message]
2020-02-17 9:10 ` [PATCH 2/3] sched/rt: allow pulling unfitting task Pavan Kondeti
2020-02-17 11:20 ` Qais Yousef
2020-02-19 13:43 ` Qais Yousef
2020-02-21 8:07 ` Pavan Kondeti
2020-02-21 11:08 ` Qais Yousef
2020-02-14 16:39 ` [PATCH 3/3] sched/rt: fix pushing unfit tasks to a better CPU Qais Yousef
2020-02-17 9:23 ` Pavan Kondeti
2020-02-17 13:53 ` Qais Yousef
2020-02-18 4:16 ` Pavan Kondeti
2020-02-18 17:47 ` Qais Yousef
2020-02-19 2:46 ` Pavan Kondeti
2020-02-19 10:46 ` Qais Yousef
2020-02-19 14:02 ` Qais Yousef
2020-02-21 8:15 ` Pavan Kondeti
2020-02-21 11:12 ` Qais Yousef
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