more processors = increased runtime ?

[NigsRpgId@xxxxxxx]

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Hi,  I have a situation where a particular part of an overnight process is
taking much longer to run on a more powerful system, and wondered if anyone
might offer any suggestions as to why this may happen.  The remaining parts
of the process are running more or less the same length of time, or slightly
better.

For one program that is called within the process, the elapsed run time is
1.5hrs on System A whereas it is 8.0 hrs on System B.

In both cases the job is run overnight when there is not much other activity
on the system. The job has been run several times with the same results, on
each system.

System A is a 4-way system, system B is a 12-way system. Both are on the same
version of OS/400 with the same CUM PTF's applied. The subsystem descriptions
should be similar and both run in the base pool.

I am waiting to hear if SMP is installed on either/both (DB2 Symmetric
multiprocessing), but since it is an RPGLE program, I don't think this will
make a difference anyway.

The program is performing input-primary processing on a join logical based on
three physical files. There is one format in the join logical. There are 11
million records in each of two of the joined files, and around 100,000 in the
other. The data has been restored from one system to the other so it is
identical.

Any ideas ??

Thanks in advance!

Nigel