It didn't take me long to find MP effect articles by typing "MP effect" i nto Google. In particular, the z/VM Performance report at <http://www.vm.ibm.com/perf/reports/zvm/zvmper f.pdf> has a section on 24-Way Support from z/VM Version 5 Release 1.0. It show graphs for 16, 18, 20, 22, and 24 processors. This section is available in HTML at <http://www.vm.ibm.com/perf/reports/zvm/html/24way.html> if you do not wa nt to download the whole PDF. This was for an HTTP server workload on a z990. Looking at the spin lock graph, it doesn't appear there would have been problem for this workload with less than 16 processors.
I don't know if that will help with Marcy's workload or not. Alan Ackerman Alan (dot) Ackerman (at) Bank of America (dot) com
