getrusage - get resource usage


   #include <sys/time.h>
   #include <sys/resource.h>

   int getrusage(int who, struct rusage *usage);


   getrusage()  returns  resource usage measures for who, which can be one
   of the following:

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

          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
          _GNU_SOURCE feature test macro must be defined (before including
          any  header  file)  in  order  to  obtain the definition of this
          constant 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:

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

          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.

          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.

          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.


   On success, zero is returned.  On error, -1 is returned, and  errno  is
   set appropriately.


   EFAULT usage points outside the accessible address space.

   EINVAL who is invalid.


   For   an   explanation   of   the  terms  used  in  this  section,  see

   Interface    Attribute      Value   
   getrusage()  Thread safety  MT-Safe 


   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.


   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).


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


   This  page  is  part of release 4.09 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


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