Lindy - > So if I have a job that uses 10 CPU seconds on a 500 MIPS machine and > I upgrade to 1000 MIPS it may only take 4 CPU seconds, no?
It depends. <g> If your old machine is five 100-MIPS CPs and your new machine is ten 100-MIPS CPs, then no, it will still take *about* 10 CPU seconds (because each CPU is the same, comprende?). But if your new machine is five 200-MIPS CPs, then it will take only *about* 5 (not 4 -- a little problem with short division here? <g>) CPU seconds. MIPS are a pure measure of processor speed: millions of CPU instructions per second. MSUs/second are a measure of "service units" per second. I'm no expert, and I'm sure the experts will chime in <g>. Service units include a "basket" of resources in addition to CPU instruction processing -- but CPU instruction processing dominates, so many people use one MSU/second = 5.7 MIPS. Because IBM charges for software based on MSUs, and because marketing folks do what marketing folks do, there has been some "fudging" on IBM's part, so the "legal" MSU rating of a particular box may differ from its measured MSU rating. Or as IBM puts it, "MSUs are used for software pricing and are not necessarily a direct indication of relative processor capacity. MSUs for the 2084, 2086, 2094 and 2096 model types are set to provide improved software price/performance for applicable programs which have MSU based pricing." Aren't you glad you asked? Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Lindy Mayfield Sent: Friday, March 30, 2007 10:01 AM To: IBM-MAIN@BAMA.UA.EDU Subject: Re: What's a CPU second? I saw this thread and thought this was a great question because I was a bit confused about CPU seconds. I've read every entry in this thread and came out more confused than when I started. Isn't the CPU time the amount of time that the CPU(s) spent doing the work? (All TCB's and all CPU's together) So if I have a job that uses 10 CPU seconds on a 500 MIPS machine and I upgrade to 1000 MIPS it may only take 4 CPU seconds, no? That's what I _think_ I've seen when a machine got upgraded, but after reading this thread I've read what I thought was that the CPU time might go up a bit after such an upgrade. Or was it an upgrade of adding additional CPU's that was in question? And in each of the answers to the OP, I never saw the term MIPS used. I saw the term MSU a lot. Are they about the same thing? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
