On 09/27/2018 05:43 PM, Wanpeng Li wrote:
On your CPU4:
scheduler_ipi()
-> sched_ttwu_pending()
-> ttwu_do_activate() => p->sched_remote_wakeup should be
false, so ENQUEUE_WAKEUP is set, ENQUEUE_MIGRATED is not
-> ttwu_activate()
-> activate_task()
-> enqueue_task()
-> enqueue_task_fair()
-> enqueue_entity()
bool renorm = !(flags &
ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATE)
so renorm is false in enqueue_entity(), why you mentioned that the
cfs_rq->min_vruntime is still added to the se->vruntime in
enqueue_task_fair()?
Maybe this is a misunderstanding on my side but didn't you asked me to
'... Could you point out when the fair rq's min_vruntime is added to the
task's vruntime in your *later* scenario? ...'
Yeah, if the calltrace above and my analysis is correct, then the fair
rq's min_vruntime will not be added to the task's vruntime in your
*later* scenario, which means that your patch is not necessary.
In the scenario I observed, the task is not waking - it is running and
being deboosted from priority inheritance, transitioning from RT to CFS.
Dietmar and I both were able to reproduce the issue with the testcase I
posted earlier in this thread.
thanks,
Steve
