getrusage(2) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | 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.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌────────────┬───────────────┬─────────┐
       │Interface   Attribute     Value   │
       ├────────────┼───────────────┼─────────┤
       │getrusage() │ Thread safety │ MT-Safe │
       └────────────┴───────────────┴─────────┘

CONFORMING TO         top

       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         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 (up
       until version 2.32) 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 5.10 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                          2020-12-21                   GETRUSAGE(2)

Pages that refer to this page: fork(2)getrlimit(2)sigaction(2)syscalls(2)times(2)wait(2)wait4(2)clock(3)pthreads(7)time(7)