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Re: [Xen-users] xen blocked state



I always assumed blocking was the same blocking that CPU scheduling uses. Meaning multiple programs want to access the resources and they can't all have them at once, and no one program can have 100% access to resources as other programs would never get CPU time. So blocking is used, such that resources are distributed evenly among the competing programs. For Xen I always assumed it was similar but Xen treats virtual machines as processes ( in dom0 ), and schedules them much like an OS would schedule programs. I am sure there is much more involved in Xen blocking. But that is how I always interpret the block state of virtual machines.
Steffen Heil wrote:
Hi

Just curious, what does "blocked" really mean? Is r "running" a state reserved for Dom0 and not DomU. I am using SLES10, and I have noticed for quite awhile that when my DomUs are running they are usually in the blocked state and never in the running state, and my Dom0 is always in the running state. The Xen user guide, explains b as blocked but doesn't really give any other detail. Is there some other doc that explains this more?

Your dom0 is always in "running" state?
How do you know?

Using xentop - thus running a software in dom0 - using the cpu for dom0 at
the very moment you get the dom list?
For sure, dom0 must be running. So, no running is not a state reserved for
dom0, domUs couldn't work at all then.
But the dom0 IS runnign at the very moment, xentop retrieves the list.
blocked means the domains are waiting for something. Processing is blocked
due to the lack of something to do.
Blocked may be waiting for keystrokes of the user, movement of the mouse,
network packets to arrive maybe even hard drive access (xen-devs, that's
right?).

Regards,
  Steffen


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