[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] Proposal for init/kexec/hotplug format for Xen

Harry Butterworth wrote:

We could begin work today on libxen-hcall and libxen-idc while we work out what the store is going to like and how the OF structure is going to work. Thoughts?

The most difficult aspect of the inter-domain communication API to
express from the point of view of forwards compatibility with a
fault-tolerant implementation is that, in a fault-tolerant system with
different levels of fault tolerance, some domains will come and go
whilst others persist across failures.

I'm not sure fault-tolerance has to be implemented at the IDC primative level. That seems like something that's implemented at a slightly higher-level in the stack.

For instance, I'm not sure how to even think about what a fault-tolerant semaphore would be however I can certainly imagine being able to implement a fault-tolerant protocol that uses semaphores and shared memory.

I think fault-tolerant primatives can quite comfortably sit on top of lower-level primatives. My initial reaction is that a fault-tolerant primative is going to have a fair bit of overhead. I think the interface is going to be fairly different too. I'm not sure you want to pay the price of transparent fault-tolerance in all circumstances.

It would probably be better to expect to implement a separate set of fault tolerant devices and just design the non-tolerant devices for maximum code-reuse.

Anthony Liguori

SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now.
Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.