NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

GETRUSAGE(2)              Linux Programmer's Manual             GETRUSAGE(2)

NAME         top

       getrusage - get resource usage

SYNOPSIS         top

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

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

DESCRIPTION         top

       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         top

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

ERRORS         top

       EFAULT usage points outside the accessible address space.

       EINVAL who is invalid.

CONFORMING TO         top

       SVr4, 4.3BSD.  POSIX.1-2001 specifies getrusage(), but specifies only
       the fields ru_utime and ru_stime.

       RUSAGE_THREAD is Linux-specific.

NOTES         top

       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         top

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

COLOPHON         top

       This page is part of release 3.73 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
       http://www.kernel.org/doc/man-pages/.

Linux                            2014-05-10                     GETRUSAGE(2)