Hello,

On Mon, Aug 24, 2015 at 02:10:17PM -0700, Paul Turner wrote:

Suppose that we have 10 vcpu threads and 100 support threads.
Suppose that we want the support threads to receive up to 10% of the
time available to the VM as a whole on that machine.

If I have one particular support thread that is busy, I want it to
receive that entire 10% (maybe a guest is pounding on scsi for
example, or in the thread-pool case, I've passed a single expensive
computation).  Conversely, suppose the guest is doing lots of
different things and several support threads are active, I want the
time to be shared between them.

There is no way to implement this with nice.  Either a single thread
can consume 10%, and the group can dominate, or the group cannot
dominate and the single thread can be starved.

Would it be possible for you to give realistic and concrete examples?
I'm not trying to play down the use cases but concrete examples are
usually helpful at putting things in perspective.

Thanks.

-- 
tejun