Messages in this thread | | | Date | Mon, 14 Dec 2015 03:13:20 +0800 | From | Yuyang Du <> | Subject | Re: PELT initial task load and wake_up_new_task() |
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Hi Steve,
On Fri, Dec 11, 2015 at 06:01:45PM -0800, Steve Muckle wrote: > In init_entity_runnable_average() the last_update_time is initialized to > zero. The task is given max load and utilization as a pessimistic > initial estimate. > > But if in wake_up_new_task() the task is placed on a CPU other than > where it was created, __update_load_avg() will be called via > set_task_cpu() -> migrate_task_rq_fair() -> remove_entity_load_avg(). > > Since last_update_time is zero the delta will be huge and the task's > load will be entirely decayed away before it is enqueued at the > destination CPU.
Since the new task's last_update_time is equal to 0, it will not be decayed.
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