dtrace discuss - Mar 2009 - unix`HYPERVISOR_sched_op -> What is my kernel doing?

Hi to everyone,

I hope you might be able to help me. I''m running several CPU and memory
intensive load tests on my machine. I''ve installed a Sun Developer
Express edition and several virtual machine with the same operating system.

Now I''m interested in what the hypervisor is doing. Therefore I
executed hotkernel (from DTrace toolkit) in DomU and Dom0. I was aliitle bit
surprised to see that the operationg "unix`HYPERVISOR_sched_op"
consumed most CPU time in both DomU and Dom0.
Now I''m wondering what is the meaning of this operation?? Can someone
explain it or give me an idea what this operation is supposed to do?

Thanks
Andr?
-- 
This message posted from opensolaris.org

On Tue, Mar 31, 2009 at 02:19:09AM -0700, Andre Boegelsack wrote:
> Now I''m interested in what the hypervisor is doing. Therefore I
> executed hotkernel (from DTrace toolkit) in DomU and Dom0. I was
> aliitle bit surprised to see that the operationg
> "unix`HYPERVISOR_sched_op" consumed most CPU time in both DomU
and
> Dom0.  Now I''m wondering what is the meaning of this operation??
Can
> someone explain it or give me an idea what this operation is supposed
> to do?
It does a number of things, but the reason you''re seeing it a lot is
because it''s the idle callback. When a virtual CPU has no work to do,
this hypercall is called. The hypervisor will then deschedule the VCPU
from running on a real CPU until an interrupt arrives.

So it looks like it''s consuming CPU, but it''s not.

regards
john