Possibilities with Xen3 compared to IBM Power5 DLPAR

[Julian Pawlowski <lists@jp-solution.net>]

Hey guys,

I'm just comparing the current development state of Xen with the established
technology from IBM on current Power5 series.
I could'nt find any information to these questions on the internet...

1. Does Xen support capacity entitlement for the CPUs, e.g.
   for processor pooling? (does Xen classify the CPU capacity
   into time slices? Would be the first step...)

2. If question 1 is "yes" or "will be in some day", is/will
   there be support for capped and uncapped domU's so that you can
   mix up things?

3. If uncapped use of a processor pool is possible, how about weighting
   different domU's? (e.g. dom0 should have uncapped mode with the
   highest weight)

4. Where can I find any further information about the dynamical
   change of active VCPUs and memory settings? E.g. What the domU
   guest system needs to have for supporting this.

5. Does Xen support SMT (simultanious multithreading) in the domU to
   also have logical processors in addition to virtual processors?
   Depends it on the physical processor so I would need a multi-core
   system which also supports SMT? But how would I control that I want to
   use SMT in some domU's and some not?

6. Can I really have a dedicated processor core assigned to dom0 or
   any domU and no other domU will use exactly that physical processing
   unit? (e.g. to make sure the L2 cache can be used more effective on
   multi-core CPUs)

I don't know which of these features have to be in hardware or can be
realized in software, so please don't blame me :-)


Maybe an interesting discussion this whole topic :-)

Looking forward to your answers!


Greetz
Julian