GETRUSAGE(2)

NAME
getrusage - get resource usage

SYNOPSIS
#include <sys/time.h>
#include <sys/resource.h>

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

DESCRIPTION

getrusage() returns current resource usages, for a who of either RUSAGE_SELF or RUSAGE_CHILDREN. The former asks for resources used by the current process, the latter for resources used by those of its children that have terminated and have been waited for.

struct rusage {
    struct timeval ru_utime; /* user time used */
    struct timeval ru_stime; /* system time used */
    long   ru_maxrss;        /* maximum resident set size */
    long   ru_ixrss;         /* integral shared 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 */
};

RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

ERRORS

EFAULT
    usage points outside the accessible address space.

EINVAL
    who is invalid.

CONFORMING TO
SVr4, BSD 4.3

NOTES
Including <sys/time.h> is not required these days, but increases portability. (Indeed, struct timeval is defined in <sys/time.h>.)

In Linux kernel versions before 2.6.9, if the disposition of SIGCHLD is set to SIG_IGN then the resource usages of child processes are automatically included in the value returned by RUSAGE_CHILDREN, although POSIX 1003.1-2001 explicitly prohibits this. This non-conformance is rectified in Linux 2.6.9 and later.

The above struct was taken from BSD 4.3 Reno. Not all fields are meaningful under Linux. In linux 2.4 only the fields ru_utime, ru_stime, ru_minflt, and ru_majflt are maintained. Since Linux 2.6, ru_nvcsw and ru_nivcsw are also maintained.

SEE ALSO
getrlimit(2), times(2), wait(2), wait4(2)