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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 file system had to perform input.

       ru_oublock (since Linux 2.6.22)
              The number of times the file system 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  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.

       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

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       description of the project, and information about reporting  bugs,  can
       be found at http://man7.org/linux/man-pages/.