Messages in this thread | | | Date | Tue, 07 May 2013 10:18:08 +0800 | From | Alex Shi <> | Subject | Re: [PATCH v5 3/7] sched: set initial value of runnable avg for new forked task |
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On 05/06/2013 06:17 PM, Paul Turner wrote: >>> >> Rather than exposing the representation of load_avg_contrib to >>> >> __sched_fork it might also be better to call: >>> >> __update_task_entity_contrib(&p->se) >>> >> After the initialization above; this would also avoid potential bugs >>> >> like the missing scale_load() above. >> > >> > Above simple change can not work. > Could you provide additional detail here? Note that the sum change I > was suggesting above was: > > __sched_fork(): > + p->se.avg.decay_count = 0; > + p->se.avg.runnable_avg_period = 1024; > + p->se.avg.runnable_avg_sum = 1024; > + __update_task_entity_contrib(&p->se); > > [ Also: move __sched_fork() beyond p->sched_reset_on_fork in sched_fork(). ]
Thanks Paul! It seems work with this change if new __sched_fork move after the p->sched_reset_on_fork setting.
But why we initial avg sum to 1024? new task may goes to sleep, the initial 1024 give a unreasonable initial value.
guess let the task accumulate itself avg sum and period is more natural. > >> > We had talked this solution months ago. And get agreement on this patch. >> > https://lkml.org/lkml/2013/2/20/48 :) > Yes, I made the same suggestion in the last round, see: > https://lkml.org/lkml/2013/2/19/176 > > Your reply there seems like an ack of my suggestion, the only > difference I'm seeing is that using __update_task_entity_contrib() as > originally suggested is safer since it keeps the representation of > load_avg_contrib opaque.
Yes, using __update_task_entity_contrib make load_avg_contrib opaque. but just initial value 1024 is a bit arbitrary. >
-- Thanks Alex
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