On Thu, Jul 09, 2015 at 02:53:14PM +0100, Morten Rasmussen wrote: > On Mon, Jul 06, 2015 at 04:12:41AM +0800, Yuyang Du wrote: > > Hi Morten, > > > > On Fri, Jul 03, 2015 at 10:34:41AM +0100, Morten Rasmussen wrote: > > > > > IOW, since task groups include blocked load in the load_avg_contrib > > > > > (see > > > > > __update_group_entity_contrib() and > > > > > __update_cfs_rq_tg_load_contrib()) the > > > > > imbalance includes blocked load and hence env->imbalance >= > > > > > sum(task_h_load(p)) for all tasks p on the rq. Which leads to > > > > > detach_tasks() emptying the rq completely in the reported scenario > > > > > where > > > > > blocked load > runnable load. > > > > > > > > Whenever I want to know the load avg concerning task group, I need to > > > > walk through the complete codes again, I prefer not to do it this time. > > > > But it should not be that simply to say "the 118 comes from the blocked > > > > load". > > > > > > But the whole hierarchy of group entities is updated each time we enqueue > > > or dequeue a task. I don't see how the group entity load_avg_contrib is > > > not up to date? Why do you need to update it again? > > > > > > In any case, we have one task in the group hierarchy which has a > > > load_avg_contrib of 0 and the grand-grand parent group entity has a > > > load_avg_contrib of 118 and no additional tasks. That load contribution > > > must be from tasks which are no longer around on the rq? No? > > > > load_avg_contrib has WEIGHT inside, so the most I can say is: > > SE: 8f456e00's load_avg_contrib 118 = (its cfs_rq's runnable + blocked) / > > (tg->load_avg + 1) * tg->shares > > > > The tg->shares is probably 1024 (at least 911). So we are just left with: > > > > cfs_rq / tg = 11.5% > > Yes, we also know that there is only one runnable task in the task group > hierarchy and its contribution is 0. Hence the rest must be from > non-runnable tasks belonging to some child group.
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