SW_PREEMPT and cpu runq

[Murty, Ravi]

Hi,

 

When a thread is being switched out and it is being preempted (e.g. time
quantum expires), why does sched_switch hold it on the current cpu? i.e.
why does the code see that it was preempted and put it back on the same
queue?

In other cases it looks to see if it can be migrated and the thread goes
back some place else. If a thread is being kicked out and there is a
perfectly idle CPU some where on the system, wouldn't it make sense to
migrate the thread?

 

Thanks
Ravi