Re: [PATCH 1/7] sched/deadline: fix try to pull pinned dl tasks in pull algorithm

From: Wanpeng Li
Date: Wed May 06 2015 - 03:29:42 EST


Ping, :)
On Mon, Apr 27, 2015 at 05:42:38PM +0800, Wanpeng Li wrote:
>How about patch 1/7? :)
>On Mon, Apr 06, 2015 at 04:53:13PM +0800, Wanpeng Li wrote:
>>Function pick_next_earliest_dl_task is used to pick earliest and pushable
>>dl task from overloaded cpus in pull algorithm, however, it traverses
>>runqueue rbtree instead of pushable task rbtree which is also ordered by
>>tasks' deadlines. This will result in getting no candidates from overloaded
>>cpus if all the dl tasks on the overloaded cpus are pinned. This patch fix
>>it by traversing pushable task rbtree which is also ordered by tasks'
>>deadlines.
>>
>>Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx>
>>---
>> kernel/sched/deadline.c | 29 ++++++++++++++++++++++++++++-
>> 1 file changed, 28 insertions(+), 1 deletion(-)
>>
>>diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>>index 5e95145..b57ceba 100644
>>--- a/kernel/sched/deadline.c
>>+++ b/kernel/sched/deadline.c
>>@@ -1230,6 +1230,33 @@ next_node:
>> return NULL;
>> }
>>
>>+/*
>>+ * Return the earliest pushable rq's task, which is suitable to be executed
>>+ * on the cpu, NULL otherwse
>>+ */
>>+static struct task_struct *pick_earliest_pushable_dl_task(struct rq *rq,
>>+ int cpu)
>>+{
>>+ struct rb_node *next_node = rq->dl.pushable_dl_tasks_leftmost;
>>+ struct task_struct *p = NULL;
>>+
>>+ if (!has_pushable_dl_tasks(rq))
>>+ return NULL;
>>+
>>+next_node:
>>+ if (next_node) {
>>+ p = rb_entry(next_node, struct task_struct, pushable_dl_tasks);
>>+
>>+ if (pick_dl_task(rq, p, cpu))
>>+ return p;
>>+
>>+ next_node = rb_next(next_node);
>>+ goto next_node;
>>+ }
>>+
>>+ return NULL;
>>+}
>>+
>> static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl);
>>
>> static int find_later_rq(struct task_struct *task)
>>@@ -1514,7 +1541,7 @@ static int pull_dl_task(struct rq *this_rq)
>> if (src_rq->dl.dl_nr_running <= 1)
>> goto skip;
>>
>>- p = pick_next_earliest_dl_task(src_rq, this_cpu);
>>+ p = pick_earliest_pushable_dl_task(src_rq, this_cpu);
>>
>> /*
>> * We found a task to be pulled if:
>>--
>>1.9.1
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