RE: Multiple jobs running out of single JOBQ are very slow

["Pete Massiello" <pmassiello-ml@xxxxxxxxxxxx>]

John,

	Its not how much capacity is on the disks, but utilization.  Find
out what the utilization is at 10 and then 25.  Most likely at 25 all you
are doing is thrashing your resources of memory and disks, remember
performance is about utilizing Memory, CPU, and Disk.  It doesn't sound like
CPU is the issue, but I bet the other two are.  What does WRKSYSSTS (make
sure you are running at option 3 not option 2 from F21 to get the best look
at WRKSYSSTS).  How is the paging when running 10 compared to 25.  How much
memory do you have in the *BASE pool and for the entire system.  What is
QPFRADJ set at 3?

Pete

Pete Massiello
iTech Solutions
http://www.itechsol.com





-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of John Allen
Sent: Monday, June 01, 2009 4:00 PM
To: MIDRANGE-L@xxxxxxxxxxxx
Subject: Multiple jobs running out of single JOBQ are very slow

First off I am not even close to a guru on system
performance tuning.

I know just enough to be dangerous

 

So I am hoping someone here can at least point me in a
direction to get me started on this issue.

 

I have a JOBQ with Max Active set to 25

Running out of Pool Id 2 (*BASE)

*BASE has 1603MB memory with max active 109

% System ASP used is 79%

I cannot seem to find where the time slice value is set so I
cannot verify the value

 

There could be up to 25 jobs submitted into the JOBQ to run
at any given time

 

If there are only 10 jobs running at the same time, they all
run very quickly (less then a minute)

But as I increase the number of jobs running at the same
time, they slow way down (10-20 minutes each)

(And they are not processing anything)

Almost seems like they are all fighting for resources and
none of them complete

When I do wrkactjob the system CPU is 14% and the jobs CPU%
vary from .0 to .2 to .4 

 

I cannot have them run single thread (or whatever 10 thread
is called) I have to allow for up to 25 running at the same
time

 

These jobs are running at priority 50 (because another
programmer said they were using up the system resources and
"slowing everything down")

 

I can change the jobq to run 10 at a time and they speed up
to the expected speed based on the little processing they
are doing

so I think it must be some system setting I need to adjust
to improve the jobs performance without affecting the
interactive jobs.

 

Any pointers?

 

 

Thanks in advance 

 

John