Neugebauer, Rolf wrote:

First of all, my suggestion was to have this as a configuration option, or even a separate implementation, providing just the ability to host domUs. I am sure this is doable, as it seems to be what coLinux is doing with some success. I was not suggestion throwing away existing functionality, but to optimize for the common case, i.e. a single Linux providing all drivers.

Secondly, there have been repeated reports on this list of people having problems with lower performance in domU than in dom0, perhaps due to cheap hardware, perhaps just due to misconfiguration, and the figures on the Xen website have not been updated to reflect what the actual situation is, so I guess nobody knows what the overhead will look like for a specific type of application. I would worry about MPI-style jobs, where you need both low latency and high bandwidth networking, and where you are likely to fully utilize the TLBs as well. I cannot see how performance does not get hurt in this situation, when Xen needs to flush the TLB for every interrupt, or alternatively needs to bundle interrupts, thus increasing latency.

Jacob