A task can only use one CPU at a time, but MVS has never limited an address space to a single CPU except for the case of CPU affinity, which I have never seen used.
However, many batch jobs do not exploit multitasking and thus cannot exploit multiple CPUs. -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of Jason Cai [ibmm...@foxmail.com] Sent: Wednesday, July 12, 2023 6:27 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: A question about CPU usage on z/OS Dear all, I have a question about CPU usage on z/OS that I hope you can help me with. Many years ago, we increased the CPU of a mainframe from one to four, but the batch jobs at night became slower. The explanation at that time was that a batch job could only use one CPU, and the single CPU performance decreased because of the increase to four CPUs. I accepted that explanation at that time. Now, twenty years later, is z/OS still the same that an address space like IXGLOGR can only use one CPU at most? Thank you for your time and attention. I look forward to hearing from you soon. Jason Cai ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
