Communicating between Dom0 and DomU without a network

Communicating between Dom0 and DomU without a network

[Hajime Inoue]

I'm looking for a way to communicate, without a network,
between Dom0 and DomU, at speeds approaching typical
bandwidth.

In August of last year, there was a discussion on this
list about the best way to communicate between Dom0 and
DomU without a network.  Using the console was suggested,
but some of the responders complained about its lack of
speed.  Someone mentioned a proposal for high speed byte
transfers between VMs, but I cannot find a record of it
being implemented.

I'd appreciate any advice on this.  What's the best way
to send large amounts of data from an HVM guest to Dom0
without a network?

Thanks,
-Hajime Inoue

Communicating between Dom0 and DomU without a network

[Hajime Inoue]

I'm looking for a way to communicate, without a network,
between Dom0 and DomU, at speeds approaching typical
bandwidth.

In August of last year, there was a discussion on this
list about the best way to communicate between Dom0 and
DomU without a network.  Using the console was suggested,
but some of the responders complained about its lack of
speed.  Someone mentioned a proposal for high speed byte
transfers between VMs, but I cannot find a record of it
being implemented.

I'd appreciate any advice on this.  What's the best way
to send large amounts of data from an HVM guest to Dom0
without a network?

Thanks,
-Hajime Inoue

RE: Communicating between Dom0 and DomU without a network

[James Harper]

> I'm looking for a way to communicate, without a network,
> between Dom0 and DomU, at speeds approaching typical
> bandwidth.

Can you detail some of the requirements? Whatever you use will require a
protocol of some sort, and the network stack already implements almost
anything you would want. Possibly the next best thing would be to run
another protocol (eg not tcp/ip) over the virtual ethernet.

If you can state why using a network is out of the question, you'll
avoid a whole load of people asking you :)

James

Re: Communicating between Dom0 and DomU without a network

[Hajime Inoue]

We have an application monitoring network activity on
the guest, and we want to send summaries about that
activity to Dom0 without adding to that activity.  We
could filter the traffic so that we exclude monitor
generated activity, but we'd rather look at everything.

We don't need much of a protocol.  All the data is
going in one direction.

Thanks,
-Hajime Inoue




James Harper wrote:
>> I'm looking for a way to communicate, without a network,
>> between Dom0 and DomU, at speeds approaching typical
>> bandwidth.
> 
> Can you detail some of the requirements? Whatever you use will require a
> protocol of some sort, and the network stack already implements almost
> anything you would want. Possibly the next best thing would be to run
> another protocol (eg not tcp/ip) over the virtual ethernet.
> 
> If you can state why using a network is out of the question, you'll
> avoid a whole load of people asking you :)
> 

Re: Communicating between Dom0 and DomU without a network

[Mark Williamson]

> We have an application monitoring network activity on
> the guest, and we want to send summaries about that
> activity to Dom0 without adding to that activity.  We
> could filter the traffic so that we exclude monitor
> generated activity, but we'd rather look at everything.
>
> We don't need much of a protocol.  All the data is
> going in one direction.

This is going to sound maybe a bit silly, but why not just add a second 
virtual network interface for sending summary information?  Or would that 
still perturb your measurements?

Otherwise, maybe some kind of arrangement with virtual disks could solve your 
problem?

Things like "XenSocket" have been proposed for shared memory network-style 
communication between domains but nothing's been merged.  You may be able to 
find patches that'd help you on the way (or you could perhaps try to roll 
your own using shared memory and grant tables).

Cheers,
Mark

> Thanks,
> -Hajime Inoue
>
> James Harper wrote:
> >> I'm looking for a way to communicate, without a network,
> >> between Dom0 and DomU, at speeds approaching typical
> >> bandwidth.
> >
> > Can you detail some of the requirements? Whatever you use will require a
> > protocol of some sort, and the network stack already implements almost
> > anything you would want. Possibly the next best thing would be to run
> > another protocol (eg not tcp/ip) over the virtual ethernet.
> >
> > If you can state why using a network is out of the question, you'll
> > avoid a whole load of people asking you :)
>
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> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel



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