Re: [Xen-devel] XenStore as a data transfer path?

[James Harper <james.harper@xxxxxxxxxxxxxxxx>]

> >
> > Can the XenStore database be accessed by domU's?
> >
> 
> >>Yes. That is how the frontend/backend devices set up their
> >>communication channels.
> 
> Are you saying that the actual data going back and forth gets put into the
> XenStore?  I thought that the XenStore was mostly used for configuration
> keyword values and such that the underlying drivers needed.
> 

Yes. It's how they set up their communication channels. The communication 
channels are shared pages of memory and event channels, but they use xenstore 
to set it up (eg so the backend can find the address of the frontend ring.

> >
> > If so, could it be used to pass small amounts of data back and forth
> between
> > dom0 and domU's using XenStore key entries?  If this is possible, it
> > would seem that this could eliminate the need to create a "device"
> > driver for a simple communication path.
> >
> 
> >>Yes, for certain values of "small". Can you say more about the sort of
> >>data you would be passing? In particular the throughput and latency
> >>requirements?
> 
> I would say that the small amount of data here per transfer would be around
> 32 bytes in length with a latency of around 500ms or so.
> 

How fast though? Is it 32 bytes every 1ms, or 32 bytes every 20 seconds?

James

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