Commit-ID: 308a623a40ce168eb234ea82c2bd13ff85a098d9
Gitweb: http://git.kernel.org/tip/308a623a40ce168eb234ea82c2bd13ff85a098d9
Author: Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx>
AuthorDate: Fri, 31 Oct 2014 06:39:31 +0800
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 4 Nov 2014 07:17:52 +0100
sched/rt: Clean up check_preempt_equal_prio()
This patch checks if current can be pushed/pulled somewhere else
in advance to make logic clear, the same behavior as dl class.
- If current can't be migrated, useless to reschedule, let's hope
task can move out.
- If task is migratable, so let's not schedule it and see if it
can be pushed or pulled somewhere else.
Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxx>
Cc: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1414708776-124078-1-git-send-email-wanpeng.li@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/rt.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index d024e6c..3d14312 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1351,16 +1351,22 @@ out:
static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
{
- if (rq->curr->nr_cpus_allowed == 1)
+ /*
+ * Current can't be migrated, useless to reschedule,
+ * let's hope p can move out.
+ */
+ if (rq->curr->nr_cpus_allowed == 1 ||
+ !cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
return;
+ /*
+ * p is migratable, so let's not schedule it and
+ * see if it is pushed or pulled somewhere else.
+ */
if (p->nr_cpus_allowed != 1
&& cpupri_find(&rq->rd->cpupri, p, NULL))
return;
- if (!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
- return;
-
/*
* There appears to be other cpus that can accept
* current and none to run 'p', so lets reschedule
--
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