Definitions for Optimizing System Performance
performance statistics
are measurements of the total input and output operations (I/O), memory, and CPU
time used to process individual DATA steps or PROC steps. You can obtain these
statistics by using SAS system options that can help you to measure your job's initial
performance and to determine how to improve performance.
system performance
is measured by the overall amount of I/O, memory, and CPU time that your system
uses to process SAS programs. By using the techniques discussed in the following
sections, you can reduce or reallocate your usage of these three critical resources to
improve system performance. You might not be able to take advantage of every
technique for every situation, but you can choose the ones that are most appropriate
for a particular situation.
Collecting and Interpreting Performance
Using the FULLSTIMER and STIMER System Options
The FULLSTIMER and STIMER system options control the printing of performance
statistics in the SAS log. These options produce different results, depending on your
operating environment. See the SAS documentation for your operating environment for
details about the output that SAS generates for these options.
The following output shows an example of the FULLSTIMER output in the SAS log, as
produced in a UNIX operating environment.
Log 12.1 Sample Results of Using the FULLSTIMER Option in a UNIX Operating
NOTE: DATA statement used:
real time 0.19 seconds
user cpu time 0.06 seconds
system cpu time 0.01 seconds
Memory 460k
Semaphores exclusive 194 shared 9 contended 0
SAS Task context switches 1 splits 0
The STIMER option reports a subset of the FULLSTIMER statistics. The following
example shows STIMER output in the SAS log.
Log 12.2 Sample Results of Using the STIMER Option in a UNIX Operating Environment
NOTE: DATA statement used:
real time 1.16 seconds
cpu time 0.09 seconds
196 Chapter 12 Optimizing System Performance

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