The Performance and Coverage Analyzer for OpenVMS (PCA) is a
software development tool that helps you analyze the run-time
behavior of application programs. PCA can pinpoint execution
bottlenecks and other performance problems in user programs.
Using this information, you can modify your programs to run
faster. This tool also measures which parts of your program are
or are not executed by a given set of test data so that you can
devise tests that exercise all parts of your program.
PCA has two operational components: the Collector and the
Analyzer. The Collector gathers performance or coverage data
on a running user program and writes that data to a performance
data file. Later, the Analyzer processes the collected data to
produce performance or coverage histograms and tables.
The DCL command 'PCA' invokes the Analyzer. The parameter to the
PCA command is the name of the performance data file to analyze.
Format
$ PCA [file-spec]
1 – Parameters
file-spec
Specifies the performance data file to be analyzed. File-spec
may be any valid OpenVMS file specification. If you omit the file
type, .PCA is used by default. If you omit the entire file-spec
parameter, you must use the Analyzer SET DATAFILE command to
specify the performance data file.
2 – Qualifiers
2.1 /COMMAND
/COMMAND="command [;command...]"
Specifies a list of Analyzer commands. The Analyzer executes
this list of commands after executing the commands in the
initialization file (if any) and before prompting for commands
from the terminal.
2.2 /INTERFACE
/INTERFACE=[interface-type]
Controls the display interface to be selected.
The default qualifier value is /INTERFACE=CHARACTER_CELL.
Qualifier Keyword Description
CHARACTER_CELL Selects the character cell interface.
DECWINDOWS Selects the DECwindows (a.k.a Motif)
interface, depending on the setting of the
various PCA*$DEC$DISPLAY and DECW$DISPLAY
logicals.
MOTIF Selects the Motif (a.k.a DECwindows)
interface, depending on the setting of the
various PCA*$DEC$DISPLAY and DECW$DISPLAY
logicals.
3 – Collector
The Collector gathers performance or coverage data from your
program at run time and writes that data to a performance data
file. To use the Collector, you must:
1. Compile your sources with the "/DEBUG" qualifier;
This puts all the necessary symbolic information PCA needs
into the object file.
2. The following steps specifies the PCA Collector as your
program's "debugger":
i Link your program with the "/DEBUG" qualifier;
ii Define the logical name LIB$DEBUG as PCA$COLLECTOR;
3. Run your program;
4. Enter the "GO" command at the PCAC> prompt.
The Collector will transfer control to your program just like
the debugger does, and will store the data in a data file
named your-image-name.PCA.
The following example illustrates the DCL commands required to
invoke the Collector on the FORTRAN program PRIMES.FOR:
$ FORTRAN/DEBUG PRIMES.FOR
$ LINK/DEBUG PRIMES.OBJ
$ DEFINE LIB$DEBUG PCA$COLLECTOR
$ RUN PRIMES.EXE
Performance and Coverage Analyzer for OpenVMS Version V5.1
PCAC>
When you get the Collector prompt (PCAC>), you have successfully
invoked the Collector and are ready to enter Collector commands.
To collect PC-sampling data, it is sufficient to enter the GO
command at this point. The Collector will create a performance
data file with the default name "image-name.PCA", where image-
name is the name of the executable image being run. This file
will contain the collected data and all symbol information needed
by the Analyzer.
PCAC> GO
%PCA-I-DEFDATFIL, set datafile required in this context,
creating '[]PRIMES.PCA'
%PCA-I-BEGINCOL, data collection begins
%PCA-I-DATADEFPC, defaulting to collecting PC sampling data
%PCA-I-ENDCOL, data collection ends
$
For more information, enter HELP at the PCAC> prompt.
4 – Analyzer
The Analyzer processes the data in a performance data file to
produce histograms, tables, and other reports. The Analyzer
enables you to interactively examine the gathered data in various
ways until performance bottlenecks are pinpointed or code not
covered by testing is identified.
To invoke the Analyzer, use the PCA command at DCL level. This
command accepts the name of a performance data file created by
the Collector as a parameter. For example, to run the Analyzer on
the performance data file PRIMES.PCA, use this command:
$ PCA PRIMES
Performance and Coverage Analyzer for OpenVMS Version V5.1
PCAA>
The PCAA> prompt indicates that The Analyzer is ready to accept
Analyzer commands. For example, the user may just enter the
NEXT command at this point. It will display a source plot of the
program's routine with the most PC-sampling data points. In the
plot, the line with the most data points will be pointed to by an
arrow (->). In other words, the NEXT command will show where the
program is spending most of the execution time.
PCAA> NEXT
Performance and Coverage Analyzer for OpenVMS Page 1
Program Counter Sampling Data (192 data points total) - "*"
Routine PRIME\PRIME
Percent Count Line
PRIME\PRIME\
0.5% 5: LOGICAL FUNCTION PRIME(N)
1.6% 6: PRIME = .TRUE.
0.5% 7: DO 10 I = 2, N/2
54.7% ******* -> 8: IF ((N - ((N / I) * I)) .EQ. 0) THEN
9: PRIME = .FALSE.
0.0% 10: RETURN
0.0% 11: ENDIF
1.0% 12: 10 CONTINUE
0.0% 13: RETURN
PCAA>
The NEXT command can now be typed again to traverse to the point
with the next largest number of data points, and so on. To
end the Analyzer session, the EXIT command or Control/Z can be
entered.
For more information, enter HELP at the PCAA> prompt.
5 – Release Notes
The release notes for PCA are located in SYS$HELP:PCAvvu.RELEASE_
NOTES (ASCII text) and SYS$HELP:PCAvvu_RELEASE_NOTES.PS
(postscript), where 'vv' represents the major version number
and 'u' the minor version number. For example, the filename for
the PCA V4.7 release notes is 'PCA047.RELEASE_NOTES'.