On Tuesday, 08/28/2007 at 09:58 EDT, Dave Jones <[EMAIL PROTECTED]> wrote: > Yes, for the most part, running in 64-bit mode will not be quite as > efficient as running the same application in 31 bit mode. CP has more > memory to keep track of, and that means larger page tables, TLBs etc. > If the guest is Linux, then Linux also has more work to do in it's > virtual storage management code as well, keeping track of the extra memory.
Well, to the extent that a z/Architecture guest can define and use more memory than a S/390 guest and consume more of the system's resources managing that memory, that's true. Otherwise, the effect of architecture mode on CP is negligible. (Even in 31-bit addressing mode a z/Architecture guest has 64-bit registers.) Of course, the CPU cache is the same size in either case, so fewer z/Architecture guests can live in it. > I would advise that you try to run your application is the smallest 31 > bit virtual machine that you can. Good advice, IMO. Alan Altmark z/VM Development IBM Endicott ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
