Messages in this thread Patch in this message | | | Subject | Re: [PATCH] sched: Make sure task has correct sched_class after policy change | From | Peter Zijlstra <> | Date | Wed, 23 Sep 2009 08:32:59 +0200 |
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On Wed, 2009-09-23 at 02:21 +0000, Peter Williams wrote: > From the code in rt_mutex_setprio(), it is evident that the intention > is that task's with a RT 'prio' value as a consequence of receiving a PI > boost also have their 'sched_class' field set to '&rt_sched_class'. > However, the code in __setscheduler() could result in this intention > being frustrated. > > This patch fixes this problem. > > Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
I think you're right, but the problem seems to be that it sets sched_class based on policy, which seems fragile in the face of PI.
How about the alternative below?
--- kernel/sched.c | 17 ++++------------- 1 files changed, 4 insertions(+), 13 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c index 91843ba..753a52c 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6129,23 +6129,14 @@ __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio) { BUG_ON(p->se.on_rq); - p->policy = policy; - switch (p->policy) { - case SCHED_NORMAL: - case SCHED_BATCH: - case SCHED_IDLE: - p->sched_class = &fair_sched_class; - break; - case SCHED_FIFO: - case SCHED_RR: - p->sched_class = &rt_sched_class; - break; - } - p->rt_priority = prio; p->normal_prio = normal_prio(p); /* we are holding p->pi_lock already */ p->prio = rt_mutex_getprio(p); + if (rt_prio(p->prio)) + p->sched_class = &rt_sched_class; + else + p->sched_class = &fair_sched_class; set_load_weight(p); }
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