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 resource usage measures for who, which can be one of the following:

RUSAGE_SELF
    Return resource usage statistics for the calling process, which is the sum of resources used by all threads in the process.

RUSAGE_CHILDREN
    Return resource usage statistics for all children of the calling process that have terminated and been waited for. These statistics will include the resources used by grandchildren, and further removed descendants, if all of the intervening descendants waited on their terminated children.

RUSAGE_THREAD (since Linux 2.6.26)
    Return resource usage statistics for the calling thread.

The resource usages are returned in the structure pointed to by usage, which has the following form:

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. POSIX.1-2001 specifies getrusage(), but only specifies the fields ru_utime and ru_stime. RUSAGE_THREAD is Linux-specific.

NOTES
Resource usage metrics are preserved across an execve(2). 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.1-2001 explicitly prohibits this. This nonconformance is rectified in Linux 2.6.9 and later.

The structure definition shown at the start of this page 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. Since Linux 2.6.22, ru_inblock and ru_oublock are also maintained. See also the description of /proc/PID/stat in proc(5).

SEE ALSO
clock_gettime(2), getrlimit(2), times(2), wait(2), wait4(2), clock(3)

COLOPHON
This page is part of release 3.24 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.