7.1;hpc (histogram_pc), revision 7.1, 84/08/28
HPC (HISTOGRAM_PROGRAM_COUNTER) -- Program counter histogram.
usage: HPC [-LOW x] [-HIGH x] [-RATE n] pathname [args...]
FORMAT
HPC [options] pathname [args...]
HPC produces a histogram of the program counter during program execution, thus
helping you locate the most time-consuming portions of your program.
While your program is executing, HPC samples the program counter at regular
intervals, gathering a set of data points. Each data point is the address at
which the program was executing -- that is, the value of the program counter
-- when the sample was taken.
When execution of your program has ended, HPC displays statistics and a
histogram (bar graph) of the program counter. Each bar corresponds to an area
of program memory. The length of the bar indicates how much time the program
spent executing in the corresponding area.
While HPC and your program are executing, serial line 3 (SIO3) (line 2 on
DN3xx systems) is not available for output.
ARGUMENTS
pathname
(required) Specify the name of the program to be evaluated.
args
(optional) Specify any arguments to be passed to the program
"pathname". These are not processed by HPC, but passed
directly to your program.
Default if omitted: no arguments passed
OPTIONS
If no options are specified, a histogram is produced for the entire program,
with 500 samples taken per second.
-LOW x Specify lowest address ("x") to be included in the
histogram. "x" must be a hexadecimal value. If this option
is omitted, the histogram starts at the beginning of the
program.
-HIGH x Specify highest address ("x") to be included in the
histogram. "x" must be a hexadecimal value. If this
option is omitted, the histogram continues to the end of
the program.
By limiting the range of addresses in the histogram with
-LOW and -HIGH, you can study a specific part of your
program, such as an I/O routine.
-RATE n Specify how many times ("n") HPC samples the program
counter per second. "n" must be a decimal number in the
range 5 to 2000. The default is 500 samples per second. A
higher rate results in a more accurate histogram, but tends
to slow program execution.
EXAMPLES
For a detailed example of HPC, see the HPC command description in the "DOMAIN
System Command Reference Manual."