Support for direct inter-VM sockets? Inter-VM shared memory?

Support for direct inter-VM sockets? Inter-VM shared memory?

[Tyler Bletsch]

I'm interested in moving some research prototypes from Xen to KVM, but 
there are a few esoteric features I'd need to do this.

First is an efficient mechanism for direct VM-to-VM sockets...something 
that bypasses the protocol stack and minimizes overhead.  Xen has 
XenSocket, XenLoop, and others.  I found a few mentions of this idea 
dating back to 2006*, mostly saying that a few people have done 
something like this as a one-off, but nothing official has been 
released.  I haven't found anything like this more recently, though.  
Has there been any progress on this front?  Ideally, I'd want a 
character device or a special program that acts as a fast pipe to a 
different VM.

Second, what about inter-VM shared memory?

Apologies if I'm missing some well known doc...I search around google & 
the wiki to no avail.

Thanks,
Tyler Bletsch

* http://www.mail-archive.com/kvm-devel@lists.sourceforge.net/msg00304.html

Re: Support for direct inter-VM sockets? Inter-VM shared memory?

[Avi Kivity]

On 05/20/2010 10:19 PM, Tyler Bletsch wrote:
> I'm interested in moving some research prototypes from Xen to KVM, but 
> there are a few esoteric features I'd need to do this.
>
> First is an efficient mechanism for direct VM-to-VM 
> sockets...something that bypasses the protocol stack and minimizes 
> overhead.  Xen has XenSocket, XenLoop, and others.  I found a few 
> mentions of this idea dating back to 2006*, mostly saying that a few 
> people have done something like this as a one-off, but nothing 
> official has been released.  I haven't found anything like this more 
> recently, though.  Has there been any progress on this front?  
> Ideally, I'd want a character device or a special program that acts as 
> a fast pipe to a different VM.
>
> Second, what about inter-VM shared memory?

Inter-VM shared memory (contributed by Cam, copied) is in the process of 
being merged.  That includes a fast interguest interrupt mechanism 
(using irqfd), so you could easily layer a fast interguest pipe on top 
of that.

It's possible to do a dedicated guest-to-guest channel using virtio and 
a dma engine, but I'm not aware of any efforts in that direction.

-- 
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