Re:Multitasking - is it worth it?

Discussion created by ca.portal.admin on Oct 2, 2008
I have a system which is purely Batch and CICS. There is no IDMS DC or =
Would multitasking bring me any advantage or would it just be an =
R16 SP6 . Z/OS 1.9. 4 processor large IBM thing - I lose track of the =
model numbers.
My system is well buffered and uses dataspaces extensively. CPU =
availability is my issue. There is no paging and I/O is not a problem.
Thanks for any tips.=20
Chris Trayler, IXD
Bank Julius Baer & Co. Ltd.
P. O. Box, CH-8010 Z=FCrich, Switzerland
Telephone +41 (0)58 887 4332, Fax +41 (0)58 887 4969 =
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Re: Multitasking - is it worth it?
"For a period of time we were seriously CPU constrained. We turned on multi-tasking, it cost us about 12% in overhead, but it improved throughput markedly working on the same CPU constrained machine. When the CPU constraint was removed after a significantly more powerful machine was brought in - we removed multi-tasking and IDMS continues to perform like the champion that it is.

As you surmise, when IDMS is waiting on an EREECB that means that it's waiting for the batch program to complete processing and issue another DML request. So this state indicates that there's not enough cycles for the batch jobs to run fast enough to keep IDMS as busy as it might otherwise be.

I'm assuming you've looked at ways not to run under CV mode. For example - if different parts of the database could be taken offline so that a number of jobs (each processing different parts of the database) could run in local mode - then you will remove some CPU load from the box as a whole - by getting rid of the CV mode and locking overhead (run in exclusive update when in local) - and this should stop them from competing with each other for CPU cycles. We have also gotten relief in the past by serialising some jobs - turns out they ran better that way then letting them thrash it out while running concurrently. Maybe there's a few things you can look at?

Cheers - Gary

Gary Cherlet
Justice Technology Services
Department of Justice, SA Government
Telephone +61 (0)8 8226 5199
Facsimile +61 (0)8 8226 5311
Mobile +61 (0)41 333 1613

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