Messages in this thread | | | From | Kirill Tkhai <> | Subject | Re: [PATCH 1/2] sched: Rework migrate_tasks() | Date | Wed, 11 Jun 2014 16:20:54 +0400 |
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11.06.2014, 15:24, "Srikar Dronamraju" <srikar@linux.vnet.ibm.com>: > * Kirill Tkhai <ktkhai@parallels.com> [2014-06-11 13:52:10]: >> Currently migrate_tasks() skips throttled tasks, >> because they are not pickable by pick_next_task(). > > Before migrate_tasks() is called, we do call set_rq_offline(), in > migration_call(). > > Shouldnt this take care of unthrottling the tasks and making sure that > they can be picked by pick_next_task().
If we do this separate for every class, we'll have to do this 3 times. Furthermore, deadline class does not have a list of throttled tasks. So we'll have to the same as I did: to lock tasklist_lock and to iterate throw all of the tasks in the system just to found deadline tasks.
>> These tasks stay on dead cpu even after they >> becomes unthrottled. They are not schedulable >> till user manually changes their affinity or till >> cpu becomes alive again. > > If we are still seeing tasks not being picked by pick_next_task(), then > can it probably mean that rq->rd was NULL?
Unthrottle functions dl_task_timer() and unthrottle_cfs_rq() put tasks and queues back. They do not look at rq->rd.
do_sched_rt_period_timer() does not unthrottle dead queue at all (they are excluded from rd).
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