RE: Performance tuning

We've been using AutoTune from Help Systems for decades. As we use it, it's pretty much set-it-and-forget-it. Of course, at this time we're blessed with an abundance of hardware horsepower, so tuning is pretty much academic.

Our main requirement is to keep interactive (including web) response time complaint-free.

In general terms, we try to give interactive/web-based tasks enough memory and CPU to keep them happy. And they seem to use whatever you give them!

We try to keep interactive / web / batch / spool applications separated, more from habit than from analysis. But it works for us. Spooling, as we learned early on, needs more memory than the early recommendations. The goal is to let spool get in, print something, and get out quickly. Normally, this is a relatively small hit on the CPU, but it does take memory to hold a bitmapped page with overlay!

Don't forget system functions! They need their own chunk of memory as well. Don't shortchange the system!

Faulting and paging rates. The most mystical part of tuning! Old guidance was that pages are not as bad as faults-- it just means the system requested something not in main memory (ie randomly accessing a record in a file (*sigh* Row in a table)). Faults mean the system's look-ahead paging algorithm missed, and something needed (like the next lines of the program, or the next record in a file being read sequentially) weren't in memory. Faulting should be kept to a minimum; Pages low enough that the users don't complain about response time!

Paul E Musselman
PaulMmn@xxxxxxxxxxxxx

-----Original Message-----
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxx> On Behalf Of Joe Pluta
Sent: Friday, November 30, 2018 1:09 PM
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Subject: Performance tuning

How do folks here analyze and tune their IBM i systems?  I'm looking for
broad recommendations as to:

1. Do it myself?  Are there enough tools available in the base O/S to do
so, and where would I start?

2. Additional IBM i licensed program options that would help with option 1.

3. Third party utilities.  I have no idea if these exist; a cursory
Google turned up nothing.

4. Third party consulting.

Please note that I don't want to use David's list to solicit for
services.  I'm just trying to get a feel for how it's done.  The last
box I tuned was a model 270 and things have evolved a little since
then.  If, though, you are someone who wishes to throw a hat in the ring
(yours or someone else's) then please feel free to send me an email
directly.