Re: Why not *SHRPOOL1? -- MIDRANGE-L

Rob - I am assuming that you use *SHRPOOL1 mainly for batch subsystem(s)...

I have been involved in performance tuning/work management for 20 years.  A
good reason to _not_ use *SHRPOOL1 for the QINTER subsystem is that you
shouldn't have batch and interactive jobs running in the same memory pool.

Batch work (like running a query, which is generally processing blocks of
data from the disk) need a longer timeslice to get any meaningful work
performed before they reach end of timeslice and get kicked out of the
processor.  Interactive jobs generally need a much smaller timeslice to get
the work done (press <Enter>, a little processing, redisplay screen).

If your user(s) are running queries interactively, that is _not_ good for
running in the *INTERACT memory pool - it causes the machine to thrash.

Wouldn't it be better to have the user(s) submit the query to run as a batch
job (in the batch subsystem that uses *SRHPOOL1)?  Or possibly have another
interactive subsystem for the power users who run query interactively, that
has its own memory pool, (along with a class id that makes their jobs run
like batch jobs (Timeslice(5000), runpty(50))?

There are various ways to get their interactive sessions to run in another
subsystem...use TFRJOB, named workstation sessions with workstation name
entries (or generic workstation name entries), routing entries, etc.

 You can end this subsystem in the evening, giving the memory back to the
*BASE pool...

Steve Landess
Austin, Texas
(512) 423-0935

----- Original Message -----
From: <rob@dekko.com>
To: "Midrange Systems Technical Discussion" <midrange-l@midrange.com>
Sent: Monday, January 27, 2003 8:10 AM
Subject: Why not *SHRPOOL1?


> On our 840 12-way we have system value QPFRADJ set to "2=Adjustment at IPL
> and automatic adjustment".  And we have the following pools:
> System    Pool    Reserved    Max
>  Pool   Size (M)  Size (M)  Active  Pool
>    1     2618.98    655.60   +++++  *MACHINE
>    2     6307.05     55.12     530  *BASE
>    3     3935.35      <.01      80  *SHRPOOL1
>    4      303.44       .00      20  *SPOOL
>    5     1835.15       .20     227  *INTERACT
>
> Actually, this does a pretty good job.  However, if you start this big
> whopping job in one subsystem, or the other, then it takes awhile until
> QPFRADJ switches memory over.  In the Rochester lab (just last week) we
> had a Query take 3 minutes until we switched QINTER to run in *SHRPOOL1.
> They were still scratching their heads to figure out how often QPFRADJ
> adjusts.  After the switch it took only a very few seconds.
>
> So now my boss asked me a good question.  Why don't we just use two pools:
>  *MACHINE and *SHRPOOL1?  And avoid that time lag of QPFRADJ.
>
> Questions and comments appreciated.
>
> Rob Berendt
> --
> "They that can give up essential liberty to obtain a little temporary
> safety deserve neither liberty nor safety."
> Benjamin Franklin
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