Item Subject: Message text
At the MPE technical roundtable in Toronto there were some questions as
to whether the performance characteristics of systems had changed under
5.0 Push.  I pointed out that the dispatcher had changed significantly
due to the implementation of the Workload Manager.  As a result, if an
organization had been issuing their own TUNE commands on system startup
(as we had done...), you may need to make some adjustments.
 
As a followup, I wanted to publish the queue settings that seem to be
working well for us.  First, let me point out that MPE queues have now
become workgroups.  If you have the Workload Manager, you have much
greater flexibility in terms of managing CPU consumption.  We have not
yet acquired this optional product.  However, the TUNE command remains
fully functional and may be used as before.
 
Our environment consists of a 995/600 with approximately 250 sessions
and up to 14 simultaneous jobs.  We use batch processing quite heavily,
even during the daytime, and it is necessary that we ensure that these
jobs can get some CPU time.  Here are our settings:
 
                    ------QUANTUM-------
QUEUE  BASE  LIMIT  MIN    MAX    ACTUAL  BOOST  TIMESLICE
-----  ----  -----  ---    ---    ------  -----  ---------
 CQ    152    220   100    100    100     OSC      200
 DQ    182    232   100    100    100     OSC      200
 EQ    182    234   100    100    100     DECAY    100
 
As you can see, there is some overlap between the CQ and the DQ/EQ to
allow jobs a shot at the processors.  Note that the CQ and DQ can
OSCILLATE, while the EQ (used for low priority jobs) does not.  The
Quantum is uniformly set at 100 milliseconds, so processes decay at a
uniform rate regardless of queue.  Also note that the timeslice is set
at the new 5.0 default value of 200, except for the low pri EQ.
 
Depending on your workload mix, you may want to eliminate, reduce or
extend the overlap between the CQ and DQ.  We intend to order the
Workload Manager, because it will allow a level of control that is
absent in the traditional MPE queue management.
 
In conclusion, the new 5.0 dispatcher works quite well, but your TUNE
settings may need refinement from the previous releases.
 
Robert Joseph
The NPD Group