MONCONTROL(3) | Library Functions Manual | MONCONTROL(3)

# NAME

`moncontrol` — control execution profile

# SYNOPSIS

`#include <sys/gmon.h>`

void
`moncontrol`(int mode);

# DESCRIPTION

An executable program compiled using the `-pg` option to cc(1) automatically includes calls to collect statistics for the gprof(1) call-graph execution profiler. Profiling begins at program startup and ends when the program calls exit. When the program exits, the profiling data are written to the file gmon.progname.pid.out, then gprof(1) can be used to examine the results.

`moncontrol`() selectively controls profiling within a program. When the program starts, profiling begins. To stop the collection of histogram ticks and call counts use `moncontrol`(0); to resume the collection of histogram ticks and call counts use `moncontrol`(1). This feature allows the cost of particular operations to be measured. Note that an output file will be produced on program exit regardless of the state of `moncontrol`().

# FILES

gmon.progname.pid.out
  execution data file

# SEE ALSO

cc(1), gprof(1), profil(2)

# CAVEATS

Do not call `moncontrol`(0) if pthread_create(3) will be called subsequently. While profiling is stopped, pthread_create(3) does not allocate the collection buffer for the new thread. This cannot be recovered by `moncontrol`(1), resulting in failure to collect the statistics for those threads.

September 2, 2025 | Debian