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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 _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:

       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 attributes(7).

       ┌────────────┬───────────────┬─────────┐
       │InterfaceAttributeValue   │
       ├────────────┼───────────────┼─────────┤
       │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 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 5.02 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/.