getrusage

GETRUSAGE(2)               Linux Programmer's Manual              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 statis-
              tics  will include the resources used by grandchildren, and fur-
              ther 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
              _GNU_SOURCE feature test macro must be defined (before including
              any  header file) in order to obtain the definition of this con-
              stant from <sys/resource.h>.

       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.

ATTRIBUTES
       For  an  explanation  of  the  terms  used  in  this  section,  see at-
       tributes(7).

       +------------+---------------+---------+
       |Interface   | Attribute     | Value   |
       +------------+---------------+---------+
       |getrusage() | Thread safety | MT-Safe |
       +------------+---------------+---------+

CONFORMING TO
       POSIX.1-2001,   POSIX.1-2008,   SVr4,   4.3BSD.    POSIX.1    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 porta-
       bility.  (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 automat-
       ically included in the  value  returned  by  RUSAGE_CHILDREN,  although
       POSIX.1-2001  explicitly prohibits this.  This nonconformance is recti-
       fied 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 5.05 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       https://www.kernel.org/doc/man-pages/.

Linux                             2017-09-15                      GETRUSAGE(2)