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 CPU time used */
               struct timeval ru_stime; /* system CPU 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 (soft page faults) */
               long   ru_majflt;        /* page faults (hard page faults) */
               long   ru_nswap;         /* swaps */
               long   ru_inblock;       /* block input operations */
               long   ru_oublock;       /* block output operations */
               long   ru_msgsnd;        /* IPC messages sent */
               long   ru_msgrcv;        /* IPC messages received */
               long   ru_nsignals;      /* signals received */
               long   ru_nvcsw;         /* voluntary context switches */
               long   ru_nivcsw;        /* involuntary context switches */
           };

       Not all fields are completed; unmaintained fields are set to  zero  by  the  kernel.   (The  unmaintained
       fields  are  provided  for compatibility with other systems, and because they may one day be supported on
       Linux.)  The fields are interpreted as follows:

       ru_utime
              This is the total amount of time spent executing in user mode, expressed in  a  timeval  structure
              (seconds plus microseconds).

       ru_stime
              This  is the total amount of time spent executing in kernel mode, expressed in a timeval structure
              (seconds plus microseconds).

       ru_maxrss (since Linux 2.6.32)
              This is the maximum resident set size used (in  kilobytes).   For  RUSAGE_CHILDREN,  this  is  the
              resident set size of the largest child, not the maximum resident set size of the process tree.

       ru_ixrss (unmaintained)
              This field is currently unused on Linux.

       ru_idrss (unmaintained)
              This field is currently unused on Linux.

       ru_isrss (unmaintained)
              This field is currently unused on Linux.

       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 (unmaintained)
              This field is currently unused on Linux.

       ru_inblock (since Linux 2.6.22)
              The number of times the filesystem had to perform input.

       ru_oublock (since Linux 2.6.22)
              The number of times the filesystem had to perform output.

       ru_msgsnd (unmaintained)
              This field is currently unused on Linux.

       ru_msgrcv (unmaintained)
              This field is currently unused on Linux.

       ru_nsignals (unmaintained)
              This field is currently unused on Linux.

       ru_nvcsw (since Linux 2.6)
              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 (since Linux 2.6)
              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.

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 specifies only 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.

       Ancient  systems  provided  a  vtimes()  function  with  a  similar purpose to getrusage().  For backward
       compatibility, glibc also provides vtimes().  All new applications should be written using getrusage().

       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 3.54 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/.