I decided to run my tests on linux-next, and my wakeup_rt tracer was broken. After running a bisect, I found that the problem commit was:
linux-next commit c365c292d059 "sched: Consider pi boosting in setscheduler()" And the reason the wake_rt tracer test was failing, was because it had no RT task to trace. I first noticed this when running with sched_switch event and saw that my RT task still had normal SCHED_OTHER priority. Looking at the problem commit, I found: - p->normal_prio = normal_prio(p); - p->prio = rt_mutex_getprio(p); With no + p->normal_prio = normal_prio(p); + p->prio = rt_mutex_getprio(p); Reading what the commit is suppose to do, I realize that the p->prio can't be set if the task is boosted with a higher prio, but the p->normal_prio still needs to be set regardless, otherwise, when the task is deboosted, it wont get the new priority. The p->prio has to be set before "check_class_changed()" is called, otherwise the class wont be changed. Also added fix to newprio to include a check for deadline policy that was missing. This change was suggested by Juri Lelli. Link: http://lkml.kernel.org/r/20140306120438.638bf...@gandalf.local.home Signed-off-by: Steven Rostedt <rost...@goodmis.org> --- kernel/sched/core.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index ee8004c..f00a032 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3197,6 +3197,7 @@ static void __setscheduler_params(struct task_struct *p, * getparam()/getattr() don't report silly values for !rt tasks. */ p->rt_priority = attr->sched_priority; + p->normal_prio = normal_prio(p); set_load_weight(p); } @@ -3206,6 +3207,12 @@ static void __setscheduler(struct rq *rq, struct task_struct *p, { __setscheduler_params(p, attr); + /* + * If we get here, there was no pi waiters boosting the + * task. It is safe to use the normal prio. + */ + p->prio = normal_prio(p); + if (dl_prio(p->prio)) p->sched_class = &dl_sched_class; else if (rt_prio(p->prio)) @@ -3264,7 +3271,8 @@ static int __sched_setscheduler(struct task_struct *p, const struct sched_attr *attr, bool user) { - int newprio = MAX_RT_PRIO - 1 - attr->sched_priority; + int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : + MAX_RT_PRIO - 1 - attr->sched_priority; int retval, oldprio, oldpolicy = -1, on_rq, running; int policy = attr->sched_policy; unsigned long flags; -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
