Just a guess till the experts chime in: Linux disk I/O activity requires more CPU time than traditional Z Operating systems - so when one guest starts driving 5000 I/O ops per second to the swap device ( FBA mode vdisk in my case ) that in itself consumes a big chunk of CPU. Then there's the additional time spent in the linux kernel itself deciding what needs to go out to swap and what needs to come back in.
let me re-emphasize this is a guess - I'd like to know the answer to this too. -- Jay Brenneman
