On Tue, Dec 17, 2013 at 04:02:58PM +0400, Kirill Tkhai wrote: > > > 13.12.2013, 19:42, "Peter Zijlstra" <peterz@xxxxxxxxxxxxx>: > > On Wed, Nov 27, 2013 at 07:59:13PM +0400, Kirill Tkhai wrote: > > > >> This patch touches RT group scheduling case. > >> > >> Functions inc_rt_prio_smp() and dec_rt_prio_smp() change (global) rq's priority, > >> while rt_rq passed to them may be not the top-level rt_rq. This is wrong, because > >> changing of priority on a child level does not guarantee that the priority is > >> the highest all over the rq. So, this leak makes RT balancing unusable. > >> > >> The short example: the task having the highest priority among all rq's RT tasks > >> (no one other task has the same priority) are waking on a throttle rt_rq. > >> The rq's cpupri is set to the task's priority equivalent, but real > >> rq->rt.highest_prio.curr is less. > >> > >> The patch below fixes the problem. > >> > >> It looks like all version have this bug, so I CC'ed stable mailing list. > > > > Yeah, I think this is right. > > > > cpupri stuff should indeed only be changed for the top level group. > > Ingo, are you going to apply this patch? Or will you give any comments? I queued it, Ingo should get it through me somewhere today if all things go well. Thanks -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html