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Just a few thoughts:
- subsystems and pools are designed to isolate workloads and provide for
separate control over each individual workload type.
If you think that your workload cannot be subdivided into distinct types
and/or you do not want to isolate these workloads, then you can live with
just two pools - *MACHINE pool for system purposes and *BASE for the rest.
- basic cycle for QPFRADJ is 20 seconds. It needs at least a couple of
cycles to see the pattern of use and take an action.
I do not think that QPFRADJ can take any action in "very few seconds".
- storage for the pool is allocated when the first subsystem which uses the
pool, starts.
If *SHRPOOL1 had significant storage size configured for it, and then you
started a subsystem in *SHRPOOL1, the pool will have storage allocated to
it all at once. This indeed can happen very quickly.
- QPFRADJ treatment of different pools is determined by pool tuning
attributes (basically second page in WRKSHRPOOL).
The further pool is from its target, the more aggressive QPFRADJ will be.
Alexei
always speaking for myself
rob@dekko.com
Sent by: To: Midrange Systems
Technical Discussion
midrange-l-bounces@m <midrange-l@midrange.com>
idrange.com cc:
Subject: Why not *SHRPOOL1?
01/27/2003 08:10 AM
Please respond to
Midrange Systems
Technical Discussion
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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