FastSort Manual

Sorting in Parallel
FastSort Manual—429834-003
6-6
Improving Performance
The SCRATCHFILES array contains an entry for a distributor-collector process scratch
file and three entries for subsort initial scratch files. You must specify at least a volume
name for each subsort initial scratch file:
INT distr^scratch[0:11] := [" "];
INT subp1^scratch[0:11] := ["$VENUS "];
INT subp2^scratch[0:11] := ["$MARS "];
INT subp3^scratch[0:11] := ["$SATURN "];
Because distributor-collector processes rarely use scratch files, you can omit the
distributor-collector scratch file name.
Improving Performance
If the automatic configuration does not sort your records fast enough, try running the
sort in the MINTIME mode. When you specify the MINTIME parameter in the RUN
command or in the SORTMERGESTART procedure, the size of the extended memory
segment for each subsort process can be up to 70 percent of the processor’s physical
memory not locked down by the operating system.
The following subsections explain how to set parameters to configure the subsort and
distributor-collector processes and to tune the configuration.
Configuring Subsort Processes
You can configure subsort processes through the SUBSORT command, through the
procedures SORTMERGESTART and SORTBUILDPARM, or through SUBSORT
DEFINEs. To get the best performance from subsort processes on your system, you
might need to specify one or more of the following:

A processor for each subsort process, preferably the processor that runs the
primary disk process for the scratch volume

A scratch file block size

The size of the extended memory segment

A location for the extended memory swap file

A copy of the SORTPROG program on a disk volume other than $SYSTEM

An execution priority