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, 4.3BSD

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 4.3BSD 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)