QPFRADJ - How to adjust the interval in which the autoadjuster willadjust

[rob@xxxxxxxxx]

(Names and other identifying information removed.)


Hi (xxxxx),

I found out a few things about QPRFADJ and thought I'd pass them along.
The adjustment was originally designed to occur every 20 seconds.  There
was a PTF, however, which changed that behavior for V5R1 and V5R2.   There
is a means to set the adjustment interval documented in the PTF
coverletter, and I will include those instructions below.   I learned that
there is very little documentation for this feature, but the APAR
coverletter (which I have included here as well) indicates the changes 
made
to the design and some of the reasons behind those changes.

The original concern while you were on site was a difference between
interactive and batch performance of a fairly intense query.  The
performance support contact I spoke with seemed to agree that based upon
the information we had, and what we saw in changing the interactive
pooling, that it was possible the changes to the adjustment period may 
have
impacted the interactive performance.   That's not a definitive 
conclusion,
but it seems to mesh quite well with our observations.

If you would like, I can have someone who knows substantially more about
this function contact you from the support center to discuss it (I am
making the assumption you already have a SupportLine contract), just let 
me
know.


The instructions for setting the adjustment interval follow (this is from
the V5R2 PTF coverletter for SI07195)
To change the tuning interval, first turn the
performance adjuster off:  CHGSYSVAL SYSVAL(QPFRADJ) VALUE('0')
Then create the following data area:  CRTDTAARA
DTAARA(QUSRSYS/QPFRADJWT) TYPE(*DEC) LEN(3 0) VALUE(60) In the
above example, 'VALUE(60)', is the number of seconds to wait
between tuning intervals.  The value can be replaced by any
whole number between 20 and 120 (including 20 and 120).  The
value can either be entered on the CRTDTAARA command, or by
using the Change Data Area (CHGDTAARA) command.  The data area
name, library, and type must match the above command exactly.
Next, turn the performance adjuster back to '2' or '3' using th
CHGSYSVAL or WRKSYSVAL command.  The new interval should now
take effect immediately.  If you want to change the tuning
interval after it has already been set, turn QPFRADJ system
value off ('0'), change the value in the data area to the new
number of seconds using CHGDTAARA, then turn the QPFRADJ system
value back on ('2' or '3').  ***IMPORTANT*** Deleting the
QUSRSYS/QPFRADJWT data area will not change the tuning interval
back to the default value of 60 seconds.  The only way to chang
the interval back to the default is to create (or change) the
QUSRSYS/QPFRADJWT data area with a value of 60, and follow the
previous instructions of turning the performance adjuster
off/on.  Once the new value has taken effect, the data area may
be deleted.



APAR coverletter for SE06919
|-------------------------------------------------------------------------------|
|      |
| APAR#:            SE06919      |
|      |
|      |
|      |
| Component:        5722SS1WM - OS/400 WORK MGMT      |
|      |
|      |
|      |
| Release(s)        R510, R520      |
|      |
|-------------------------------------------------------------------------------|



Abstract
OSP R510 CHANGE TO HOW OFTEN QPFRADJ WILL MOVE MEMORY.



Error Description
******* (Do NOT alter/erase this or next 3 lines) *******
* EQUIVALENT ABSTRACT:
OSP R510 CHANGE TO HOW OFTEN QPFRADJ WILL MOVE MEMORY_
*
At R510, a change to how often the performance adjuster will
move memory.  At R450 and earlier, data was moved ever 20
seconds where at R510, it is every 60 seconds.  If the request
is for 1 Gig or more, 120 seconds.INST LVL/SU= 510
QPFRADJ





Problem Summary
At R510, a change was made to how often the performance adjuster
will move memory.  At R450 and earlier, the interval was 20
seconds where at R510, it is every 60 seconds.  If the request
is for 1 Gig or more, 120 seconds.  For some workloads, this is
too slow.





Problem Conclusion
The change to the tuning interval was made in V5R1 to fix a
problem with the adjuster inappropriately responding to the
paging caused by memory movement.  The new tuning interval is
the recommended interval.  But this PTF will allow users to
change the interval to meet their specific needs.  The interval
can now be set to any value between 20 and 120 seconds.  If more
than 1 Gig of memory is moved during any given interval, the
system will still wait 120 seconds.


Temporary Fix


Comments


Circumvention










PTFs Available
R510 SI07207   1000
R520 SI07195   1000

Affected Modules
ROCSMGR

Affected Publications



Summary Information
Status................. CLOSED  PER
Severity............... 4
HIPER.................. No
PIN.................... Yes
Reported Component..... 5722SS100
Fixed Component........ 5722SS1WM
Failing Module......... ROCSMGR
Reported Release....... R510
Reported Release PTF... SI07207
Latest Release PTF.....
FESN................... 0907933
Duplicate Of...........

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(xxxxxxx)
Software Engineer, IBM - Rochester, MN
External: (xxx) xxx-xxxx    Internal t/l:  x-xxx-xxxx
On PST Temp Assignment Jan 2003 - Apr 2003
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