On Mon, 22 Dec 2008 08:25:44 -0800, Peter Duffy <[email protected]> wrote:
>Hello, Gerhard, > >Perhaps I wasn't completely clear, how about substituting the word >"equivalent" for "equal"? Can you consider choosing now? > >I used the concept of MIPS being about the same to be a short hand for the >amount of measurable work done by the 3 CPU system is about the same as the >5 CPU system, MSUs, MIPS etc all are about the same number. > >If you had a pile of money to spend on one of two ROUGHLY equal boxes, one >with 3 available CPUs and the other with 5, that being the only practical >difference, which would you want, given the workload I described and the >potential for some growth by adding fairly large workloads to the machine >probably necessitating upgrades. > >Thanks, >/ptd "It depends". I always want at least two CPUs just in case a high priority STC soaks the machine. I've had this happen. My usual diagnostic is to use BMC's SYSPROG to do a quick look at who is using the CPU and then taking the appropriate action. If I only have one cpu, then the RESOLVE stc would likely not be able to help me. If my main desire is to push though a single or small number of concurrent jobs, then I'd have fewer CPUs. This is especially true if I have a single "beloved" CICS region. Most CICS application code still runs on the QR TCB and is single threaded from a z/OS viewpoint. If what I have is a larger number of not so critical jobs (or processes), then I might decide to go with more engines. The plus of this is that the jobs would actually run simultaneously on multiple engines. This would reduce the task switch overhead. Which would also tend to keep the CPU caches loaded. I would think that a shop which is heavily WebSphere oriented might consider this. Also, consider the use of speciality engines. If I had DB2, then I want a zIIP or maybe more. If I used much Java, then I want a zAAP. The plus of these is that I have more power for my application without running up my software costs. -- John ---------------------------------------------------------------------- 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
