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Re: [Xen-devel] RFC: "local" communications

To: Anthony Liguori <aliguori@xxxxxxxxxx>
Subject: Re: [Xen-devel] RFC: "local" communications
From: Nivedita Singhvi <niv@xxxxxxxxxx>
Date: Wed, 15 Jun 2005 14:31:10 -0700
Cc: Lon Hohberger <lhh@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
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Anthony Liguori wrote:
Rik van Riel wrote:


When combining clustering with cluster storage, the situation
arises where virtual machines are not only managed by the cluster
software, but also need to participate in the cluster software

In order for this to work better, it would be good if there
was a way for software in a domU to communicate with software
on the local dom0 - so after being migrated elsewhere, a guest
would start talking to the new dom0 automatically.

Rik, is this a heartbeat kind of protocol or some such thing?
Is there value to making it be a generic solution that would
work when communicating in a non-xen environment?

Should it be some virtual device analogous to the virtual
network driver, or should we have some other kind of socket
for node local communications ?

Using protocols like TCP for node-local comms is undesirable
as TCP is engineered for the heavy machinery of the Internet.
UDP or raw sockets will be somewhat better, although AF_UNIX
would be best of all (albeit with its own constraints).

What kind of approach would the Xen community (that's you, if
you read this far) prefer ?
I can only speak for myself, but I'd personally like to see a small userspace library that established a datagram connection between two domains (using an event channel and a shared page) that could be reused for many applications.

Which datagram service, Anthony?  Having a small lib like this
would be a good idea, although the benefit would be in the details,
and of course, depending on how many apps we need to support that
we don't want to modify...

If it could be used with normal read/write calls that would be even better (although first thought is that that would require a daemon).

Probably don't want to do that...


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