RE: Auto Tuning

> from: "Ingvaldson, Scott"
> Speaking only for myself, I will never turn off
> QPFRADJ.  If you set appropriate limits it does
> its job well and there is no way manual tuning
> can keep abreast of your system as it changes
> throughout the day.

I tend to agree.  About the only thing we can do with manual tuning anyway
is to rob Peter to pay Paul.  Paul's performance may improve, but at the
expense of Peter.  Auto tuning helps establish some overall equity between
jobs of similar classes.

No matter how much memory manually allocate to a pool, overall memory
remains the same.  Adding memory to one pool always takes from another.

No matter how low the pool activity level is set, it doesn't reduce the
number of threads competing for pool resources.

No matter how high the activity level is set, it doesn't increase resources
required to support concurrently active threads.  Higher activity levels
increase the probability of paging.

No matter how low or high a time slice is set, the overall CPU time required
to complete a process remains the same.  Adjusting the time slice always
makes somebody wait longer for their chance to run.

Manual tuning may be considered a black art because it creates the illusion
of better performance.  Someone will say their performance improved.
Hopefully the guy who was adversely affected never shows up to complain.

Bottom line, tuning is practically irrelevant in comparison to writing
efficient code, and using efficient interfaces.  Tuning creates an illusion
of performance, while efficient interfaces actually reduce CPU time and
memory requirements within applications, often dramatically so.

Nathan.