Path: utzoo!mnetor!uunet!husc6!rutgers!ucla-cs!zen!ucbvax!RITA.ACS.WASHINGTON.EDU!WIZARD From: WIZARD@RITA.ACS.WASHINGTON.EDU (The Bandit "." "." "." "", on" "RITA) Newsgroups: comp.os.vms Subject: Performance and batch jobs. Message-ID: Date: 18 Dec 87 09:51:25 GMT Sender: usenet@ucbvax.BERKELEY.EDU Organization: The ARPA Internet Lines: 44 Michael J. Porter writes: > We have all our users submit heavy crunch jobs as batch. The batch > queues have a lower priority than interactive, so our interactive > users are not affected. Putting CPU time limits on users will > insure that they submit jobs. We simply threatened to do this and > our users cooperated making life easier for all. Here at the University of Washington, we have set the batch queue base priority to 3, while user's normal base priority is 4. We also have a batch job limit of three jobs in execution. This works in most instances, but you have to realize that base priority is not the only factor involved. The base priority (currently) only determines when the job will get the CPU. An example will illustrate the problem. We had a user here who submitted three batch jobs, and the system died. Setting the base priority to 0 did not help. Suspending the processes did. All three batch jobs were running a BASIC program the user had written, and all three were executed through the BASIC interpreter, rather than being compiled and linked. The program's job was to resequence another BASIC program. The problem was that the virtual working set for these jobs was huge, and the jobs were causing page faults like crazy. BASIC was installed, and page sharing wasn't the problem. The jobs just didn't want the same pages at the same time. Why did the user submit 3 jobs? Because they ran at a lower priority, and thus wouldn't affect anyone. (ha!) Why didn't the user compile and link his program? Because he couldn't LINK it. He was only 20,000+ blocks over his disk quota (which was about 2000 blocks). (Most languages get installed here with EXQUOTA, but not the linker.) Derek Haining Academic Computing Services University of Washington Seattle, Washington DEREK@UWARITA.BITNET -or- DEREK@RITA.ACS.WASHINGTON.EDU