Commit-ID: 7abc63b1bd412f7655b62ef3e35c3c11c5134636
Gitweb: http://git.kernel.org/tip/7abc63b1bd412f7655b62ef3e35c3c11c5134636
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Tue, 18 Oct 2011 22:03:48 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 1 Mar 2012 10:28:02 +0100
sched/rt: Do not throttle when PI boosting
When a runqueue has rt_runtime_us = 0 then the only way it can
accumulate rt_time is via PI boosting. That causes the runqueue
to be throttled and replenishing does not change anything due to
rt_runtime_us = 0. So avoid that situation by clearing rt_time and
skip the throttling alltogether.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
[ Changelog ]
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-7x70cypsotjb4jvcor3edctk@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/sched/rt.c | 20 ++++++++++++++++++--
1 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 6d1eb0b..7f7e7cd 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -857,8 +857,24 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
return 0;
if (rt_rq->rt_time > runtime) {
- rt_rq->rt_throttled = 1;
- printk_once(KERN_WARNING "sched: RT throttling activated\n");
+ struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
+
+ /*
+ * Don't actually throttle groups that have no runtime assigned
+ * but accrue some time due to boosting.
+ */
+ if (likely(rt_b->rt_runtime)) {
+ rt_rq->rt_throttled = 1;
+ printk_once(KERN_WARNING "sched: RT throttling activated\n");
+ } else {
+ /*
+ * In case we did anyway, make it go away,
+ * replenishment is a joke, since it will replenish us
+ * with exactly 0 ns.
+ */
+ rt_rq->rt_time = 0;
+ }
+
if (rt_rq_throttled(rt_rq)) {
sched_rt_rq_dequeue(rt_rq);
return 1;
--
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