On Fri, Oct 09, 2020 at 10:41:11PM +0200, Dietmar Eggemann wrote: > On 05/10/2020 16:57, Peter Zijlstra wrote: > > Since we now migrate tasks away before DYING, we should also move > > bandwidth unthrottle, otherwise we can gain tasks from unthrottle > > after we expect all tasks to be gone already. > > > > Also; it looks like the RT balancers don't respect cpu_active() and > > instead rely on rq->online in part, complete this. This too requires > > we do set_rq_offline() earlier to match the cpu_active() semantics. > > (The bigger patch is to convert RT to cpu_active() entirely) > > > > Since set_rq_online() is called from sched_cpu_activate(), place > > set_rq_offline() in sched_cpu_deactivate().
> [ 76.215229] WARNING: CPU: 1 PID: 1913 at kernel/irq_work.c:95 > irq_work_queue_on+0x108/0x110 > [ 76.341076] irq_work_queue_on+0x108/0x110 > [ 76.349185] pull_rt_task+0x58/0x68 > [ 76.352673] balance_rt+0x84/0x88 > balance_rt() checks via need_pull_rt_task() that rq is online but it > looks like that with RT_PUSH_IPI pull_rt_task() -> tell_cpu_to_push() > calls irq_work_queue_on() with cpu = rto_next_cpu(rq->rd) and this one > can be offline here as well now. Hurmph... so if I read this right, we reach offline with overload set? Oooh, I think I see how that happens..
