sched/rt: Do not throttle when PI boosting
tip-bot for Peter Zijlstra
maintainerCommit-ID: 7abc63b1bd412f7655b62ef3e35c3c11c5134636 Gitweb: http://git.kernel.org/tip/7abc63b1bd412f7655b62ef3e35c3c11c5134636 Author: Peter Zijlstra <[email protected]> AuthorDate: Tue, 18 Oct 2011 22:03:48 +0200 Committer: Ingo Molnar <[email protected]> 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 <[email protected]>
[ Changelog ]
Signed-off-by Thomas Gleixner <[email protected]>
Signed-off-by Ingo Molnar <[email protected]>
--- kernel/sched/rt.c | 20 ++++++++++++++++++-- 1 files changed, 18 insertions(+), 2 deletions(-)
kernel/sched/rt.c +18 -2
@@ -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 ;