RE: CPU utilization, Priority, and Throughput

Thanks for your reply.  The experience I related with the JDE OneWorld UBE
jobs is true today, as far as I know.  I was true on V4R4 a few months ago.

Richard Jackson
mailto:richardjackson@richardjackson.net
www.richardjacksonltd.com
Voice: 1 (303) 808-8058
Fax:   1 (303) 663-4325

-----Original Message-----
From: owner-midrange-l@midrange.com
[mailto:owner-midrange-l@midrange.com]On Behalf Of watern@cbs.fiserv.com
Sent: Tuesday, July 18, 2000 9:23 AM
To: MIDRANGE-L@midrange.com
Subject: Re: CPU utilization, Priority, and Throughput





Hi Richard,

you wrote... ...
<snip> ..  a  workaround recommendation arose for the "UBEs hog the CPU"
problem
- change the time slice to 200 milliseconds.  It helps but it isn't a cure.
<endsnip>..

Strangly enough, this is exactly the strategy that I remember being adopted
in
the case I described, as recommended by a performance tuning expert who I am
sure was brought in from IBM to advise.

What actually happened was I developed this application out of hours, mostly
weekends, and so was normally the only user signed on to the machine for
most of
the time that it was being developed. During my testing I didnt notice any
performance problems at all !!   I completed my work one weekend, and at
9:20am
on the first Monday that testing took place, I got a frantic phone call
saying
that when the route-planner was running the system seemed to completely
hang.

IBM were called in to advise and my understanding of their explanation was
as I
described previously.

There recommendation was.. when the job is about to become cpu-bound -
change
the timeslice to 200ms, and lower the job priority to 51. More or less just
as
you described above !  Their reasoning as I remember it was that this would
mean
that the route-planner would take all the available resource, but would give
plenty of opportunity for other jobs to grab the CPU whenever they needed
it.

This was back in 1991/92 so that is why I mentioned that it may no longer be
the
case - with all the advances since then I would not be at all surprised if
something was done about this behaviour at some point. I dont remember
hearing
about a pre-emptive feature of the AS400 job despatcher at that time and
that
would go against what we were experiencing then.

The approach suggested by the performance expert was adopted and worked very
well.

It is interesting to hear of your similar experience.. I hope that someone
may
be able to confirm how the work management function handles this scenario
now,
in the year 2000!

Rgds,
Nigel


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