GETRUSAGE(2)

GETRUSAGE(2) | System Calls Manual | GETRUSAGE(2)

# NAME

getrusage — get information about resource utilization

# LIBRARY

Standard C Library (libc, -lc)

# SYNOPSIS

#include <sys/resource.h>

#define RUSAGE_SELF 0
#define RUSAGE_CHILDREN -1

int
getrusage(int who, struct rusage *rusage);

# DESCRIPTION

getrusage() returns information describing the resources used by the current process, or all its terminated child processes. The who parameter is either RUSAGE_SELF or RUSAGE_CHILDREN. The buffer to which rusage points will be filled in with the following structure:

    struct rusage {
            struct timeval ru_utime; /* user time used */
            struct timeval ru_stime; /* system time used */
            long ru_maxrss;          /* max resident set size */
            long ru_ixrss;           /* integral shared text memory size */
            long ru_idrss;           /* integral unshared data size */
            long ru_isrss;           /* integral unshared stack size */
            long ru_minflt;          /* page reclaims */
            long ru_majflt;          /* page faults */
            long ru_nswap;           /* swaps */
            long ru_inblock;         /* block input operations */
            long ru_oublock;         /* block output operations */
            long ru_msgsnd;          /* messages sent */
            long ru_msgrcv;          /* messages received */
            long ru_nsignals;        /* signals received */
            long ru_nvcsw;           /* voluntary context switches */
            long ru_nivcsw;          /* involuntary context switches */
    };

The fields are interpreted as follows:

ru_utime
  the total amount of time spent executing in user mode.
ru_stime
  the total amount of time spent in the system executing on behalf of the process(es).
ru_maxrss
  the maximum resident set size used (in kilobytes).
ru_ixrss
  an “integral” value indicating the amount of memory used by the text segment that was also shared among other processes. This value is expressed in units of kilobytes * ticks-of-execution.
ru_idrss
  an integral value of the amount of unshared memory residing in the data segment of a process (expressed in units of kilobytes * ticks-of-execution).
ru_isrss
  an integral value of the amount of unshared memory residing in the stack segment of a process (expressed in units of kilobytes * ticks-of-execution).
ru_minflt
  the number of page faults serviced without any I/O activity; here I/O activity is avoided by “reclaiming” a page frame from the list of pages awaiting reallocation.
ru_majflt
  the number of page faults serviced that required I/O activity.
ru_nswap
  the number of times a process was “swapped” out of main memory.
ru_inblock
  the number of times the file system had to perform input.
ru_oublock
  the number of times the file system had to perform output.
ru_msgsnd
  the number of IPC messages sent.
ru_msgrcv
  the number of IPC messages received.
ru_nsignals
  the number of signals delivered.
ru_nvcsw
  the number of times a context switch resulted due to a process voluntarily giving up the processor before its time slice was completed (usually to await availability of a resource).
ru_nivcsw
  the number of times a context switch resulted due to a higher priority process becoming runnable or because the current process exceeded its time slice.

# NOTES

The numbers ru_inblock and ru_oublock account only for real I/O; data supplied by the caching mechanism is charged only to the first process to read or write the data.

# ERRORS

getrusage() returns -1 on error. The possible errors are:

[EINVAL]
  The who parameter is not a valid value.
[EFAULT]
  The address specified by the rusage parameter is not in a valid part of the process address space.

# SEE ALSO

gettimeofday(2), wait(2)

# HISTORY

The getrusage() function call appeared in 4.2BSD.

# BUGS

There is no way to obtain information about a child process that has not yet terminated.

June 4, 1993 | NetBSD 5.99