>>> On 1/28/2009 at 9:57 AM, Robert J Brenneman <[email protected]> wrote: > 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.
My experience isn't that it's the CPU cost of the paging I/O. It's more that Linux, like any other virtual storage operating system, can get into a thrashing mode, and all the kernel is doing is lots and lots of memory management. The system runs at 100% busy, and nothing gets done. Mark Post
