If CPUs are mapped around, how are IPIs handled? I assume they must be
emulated?
I've noticed that under Xen (on both Amazon EC2 and a Redhat server)
whenever you schedule a thread it always sits on the run queue for 20
uSecs before it starts running. It looks to me like it's the IPI
taking a long time to be emulated.
We have some workloads where there is a lot of flipping back and forth
between threads and they are slowed down by an order of magnitude due
to this..
turning off NOADAPTIVE(mumble) seems to help a bit as some of the
reschedules go away, but it's still a problem.
Does anyone know if BHyVe or HyperV also have this problem? I have not
yet gone to the source of Xen to see what it does but it would be
educational to know what the other Hypervisors do.
_______________________________________________
[email protected] mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization
To unsubscribe, send any mail to
"[email protected]"
