Tom, Thanks for catching my mistake. I read too quickly. Yes, the SRM constants aren't speed ratings at all.
The part that is relevant is this: the ratio of MIPS per CP is the best way for Charles to estimate the CPU time of his job on the new processor. As another lister pointed out, batch jobs generally run on a single TCB, so they can only be served as fast as a single CP can deliver. I took the average MIPS/CP from one of Cheryl Watson's CPU charts just to give a simple example. The result should be close, although in practice I have always had to compare actual job CPU times and derive the local fudge factor as closely as possible through experimentation. db -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Tom Marchant Sent: Wednesday, July 18, 2012 7:41 PM To: [email protected] Subject: Re: Help with elementary CPU speed question On Wed, 18 Jul 2012 18:47:13 -0400, Dave Barry wrote: >In theory, you divide the rated SU/second by the number of processors >giving SUs/processor/second, adjusting for "MP effect" overhead. No, the SU/second is called the SRM constant and it is used to convert CPU time (in seconds) to service units. It is already adjusted for the MP effect. Mark gave a reference earlier that describes this. Here it is again: http://publib.boulder.ibm.com/infocenter/zos/v1r11/index.jsp?topic=/com.ibm.zos.r11.erba900/erbzpm8020.htm http://tinyurl.com/ccsgeb4 >273.8 (2064-2C3) divided by 426.1 (2094-722) equals 0.643. Where did you get those numbers? The SRM constant for a 2094-722 is 19,777.5031 SU/second The SRM constant for a 2064-2C3 is 13,377.9264 SU/second Here are a few others. It should be obvious that it does not make sense to divide by the number of processors: 2064-2C1 (1 CP) 14692.3783 2064-2C2 (2 CP) 13961.6056 2064-2C3 (3 CP) 13377.9264 2064-2C4 (4 CP) 13082.5838 -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
