On Thursday, 05/18/2006 at 10:03 ZE2, Martin Schwidefsky <[EMAIL PROTECTED]> wrote: > The cache is a different story. Mainframes have the advantage of a > shared level 2 cache compared to x86. If a process migrates from one > processor to another, the cache lines of the process just have to be > loaded from level 2 cache to level 1 cache again before they can be > accessed. On x86 it goes over memory.
The cache designs on the mainframe change from generation to generation to deal with more work, changes in the relationship of CPU speed to memory speed, and more CPUs. You want the benefits of cache, but you want to minimize the serialization/synchronization effects on the processors. This is why we do our best to dispatch a virtual machine on the same CPU as was used in the previous time slice. The relationship between the CPUs and a particular cache is not always equal, but is always the best if you use the same CPU again. 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
