• Subject: RE: Performance solutions through hardware
  • From: Dwight Slessman <dslessman@xxxxxxxxxxxxxxxxxxxxxx>
  • Date: Tue, 20 Jul 1999 08:39:08 -0400
  • Organization: National Electrical Carbon Products, Inc.

Is the same job consistently slow or does it run quickly sometimes and slow 
other times?  We have found many areas of BPCS that use very poor 
programming techniques in general and SQL in particular.  The As/Set case 
tool (we have been using since 1992) does not generate the world's most 
efficient code to begin with.  Add to that some "creative" techniques used 
by SSA and you get some real dogs.  We had a sizing problem with our AS/400 
and would experience intermittant performance problems.  If your 
performance comes and goes you could also be experiencing a "governing" 
effect supplied by IBM.  When your job appears to "go to sleep", use 
WRKSYSACT and check if there are any CFINTxx jobs running and how much CPU 
they are pulling.  If you see multiple CFINTxx jobs running and they are 
pulling a significant percentage of CPU, you are being slowed down by IBM 
which would probably indicate your interactive workload is heavier than is 
recommended with your AS/400.  When this situation occurs, not only 
interactive will slow down but batch as well.  Until we were able to 
upgrade, we forbid any interactive AS/400 queries, any interactive BPCS 
jobs, etc.  This helped but we eventually had to sign the check and 
upgrade.  By the way we are on BPCS 6.0.04 mixed mode with an AS/400 2178.

Regards,

Dwight Slessman


-----Original Message-----
From:   fkolmann@revlon.com.au [SMTP:fkolmann@revlon.com.au]
Sent:   Monday, July 19, 1999 11:05 PM
To:     BPCS-L@midrange.com
Subject:        Re: Performance solutions through hardware




> I have recently been to several IBM classes & the instructors still 
define
> INTERACTIVE = Human being interacting with the computer, whether twinax 
or PC
> is the work station
> BATCH = the job is running without a work station in the picture, like 
off of
> a JOBQ

Thanks for the defnition Al.  I see nothing has changed.  We certainly use 
QINTER
QBATCH sbs
as they should.  I have started from S3 cvtd to S38 Cvtd to AS400 so I am
familiar with all AS400
concepts.


> >  To be precise,
> >  if a programmer reads an entire file sequentially to update a record
> >  rather than using a logical file to get to just the record that needs
> > updating, how will changing the CPU fix the problem.
>
> In this example, the correct solution is through software, although 
hardware
> can make the extremely inefficient process get done sooner.
>

Thank you for your reply. My point is that with SQL many programmers are 
not
setting
up appropriate indexes thus forcing  DB2/400 to create and destroy indexes 
on the
fly for each
get or update of a record via SQL.  It is the ease with which SQL allows 
such a
condition to occure
and the careless approach of some coders, as evidenced by the actual code 
that is
the problem.
Luckily the AS400 DB has a ability to hunt for access paths the can 
facilitate a
query.  This function
was not in the early AS400s and one had to be very careful about Indexes 
(lgl
files). Today it seems
that code gets written and only when the user has a problem are the LGL 
files
created. No one
has explicetly told us this is the case.  This is not to mention IBM bugs 
(that
have been since fixed) where the
optimisating (hunting) logic did not find the optimum index.


>
> > knew a thing or 2 but this stuff is like the X-Files to me, or am I 
paranoid
> again.
> Some jobs may appear to be in a wait condition if their access to system
> resources have a low priority.  Check out the rules in *JOBD for the JOBQ 
a
> batch is in.  This sort of topic is covered by IBM AS/400 classes in 
System
> Operator, Work Management, System Administration etc.
>
> http://www.training.ibm.com/ibmedu/spotlight/as400.html = IBM's 
curriculum on
> AS/400 complexities
>
> Al Macintyre

Thanks Al , you reply has restored hope to me.  I know all the stuff about 
JOBDs
JOBQs CLASSes
SBS  ROUTING ENTRIES priorities etc.  I know about disk arms and DB access
positioning files for optimum acceses ,
sorting into most used sequence and buffering(double or otherwise).  Thats 
what
makes the problems that
SQL causes so hard to understand.  SQL has the coding methods to avoid poor
performance, but it is very
easy to cause poor perfromance with SQL.


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