summaryrefslogtreecommitdiffstats
path: root/kernel/sched
diff options
context:
space:
mode:
authorWanpeng Li <wanpeng.li@linux.intel.com>2015-05-13 14:01:01 +0800
committerIngo Molnar <mingo@kernel.org>2015-06-19 10:06:45 +0200
commit8b5e770ed7c05a65ffd2d33a83c14572696236dc (patch)
tree861a74f878283f7c2f2b23bcdf7f365667275b7b /kernel/sched
parent1cde2930e15473cb4dd7e5a07d83e605a969bd6e (diff)
downloadop-kernel-dev-8b5e770ed7c05a65ffd2d33a83c14572696236dc.zip
op-kernel-dev-8b5e770ed7c05a65ffd2d33a83c14572696236dc.tar.gz
sched/deadline: Optimize pull_dl_task()
pull_dl_task() uses pick_next_earliest_dl_task() to select a migration candidate; this is sub-optimal since the next earliest task -- as per the regular runqueue -- might not be migratable at all. This could result in iterating the entire runqueue looking for a task. Instead iterate the pushable queue -- this queue only contains tasks that have at least 2 cpus set in their cpus_allowed mask. Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com> [ Improved the changelog. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1431496867-4194-1-git-send-email-wanpeng.li@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/deadline.c28
1 files changed, 27 insertions, 1 deletions
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 890ce95..9cbe1c7 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1230,6 +1230,32 @@ next_node:
return NULL;
}
+/*
+ * Return the earliest pushable rq's task, which is suitable to be executed
+ * on the CPU, NULL otherwise:
+ */
+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 +1540,7 @@ 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:
OpenPOWER on IntegriCloud