Thread in hypervisor

Thread in hypervisor

[Sangmin Lee]

Hi all,
I would like to run some tasks in context of hypervisor.
I saw some suggested to use timer but timer function seems to run in 
context of a domain which is currently running.
What I want is something like kernel thread in hypervisor,( hypervisor 
thread :-) ).
Does anyone have any idea on this?
Thanks,
Sangmin

Re: Thread in hypervisor

[George Dunlap]

The Linux kernel is that the Linux kernel keeps kernel process stacks,
so you can have a "kernel thread".  Xen does not keep in-hypervisor
stacks around -- once Xen returns to domain-space, all context is
completely gone.  So there can be no 'hypervisor threads'.  (It's a
weird concept to get used to at first.)

So your options are basically, to create a specialized domain to do
whatever "thread" activity you want done, or to use a timer function
to do the same thing.

What kind of a task are you talking about?

 -George

On 4/17/07, Sangmin Lee <sal008@cs.ucsd.edu> wrote:
> Hi all,
> I would like to run some tasks in context of hypervisor.
> I saw some suggested to use timer but timer function seems to run in
> context of a domain which is currently running.
> What I want is something like kernel thread in hypervisor,( hypervisor
> thread :-) ).
> Does anyone have any idea on this?
> Thanks,
> Sangmin
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>

Re: Thread in hypervisor

[Mark Williamson]

> I would like to run some tasks in context of hypervisor.
> I saw some suggested to use timer but timer function seems to run in
> context of a domain which is currently running.
> What I want is something like kernel thread in hypervisor,( hypervisor
> thread :-) ).

Xen's traditionally been event-driven, but I think there's a feeling that 
hypervisor threads may happen at some point.  I don't know what the details 
are though.  (side note: IIRC, there was a load balancer design that used the 
idle domain as a "hypervisor thread" - maybe you could hack something in 
there?)

The other possibility, I guess, is that depending on what you want to do you 
might be able to add a hypercall interface so that the "thread context" can 
be a kernel / user thread in dom0.

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!