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GETRUSAGE(2)                BSD System Calls Manual               GETRUSAGE(2)

NAME
     getrusage -- get information about resource utilization

SYNOPSIS
     #include <&lt;sys/resource.h>&gt;

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

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

           RUSAGE_SELF      Resources used by the current process.

           RUSAGE_CHILDREN  Resources used by all the terminated children of
                            the current process.

           RUSAGE_THREAD    Resources used by the current thread.

     The buffer to which rusage points will be filled in with the following
     structure:

     struct rusage {
             struct timeval ru_utime; /* user time used */
             struct timeval ru_stime; /* system time used */
             long ru_maxrss;          /* max resident set size */
             long ru_ixrss;           /* integral shared text memory size */
             long ru_idrss;           /* integral unshared data size */
             long ru_isrss;           /* integral unshared stack size */
             long ru_minflt;          /* page reclaims */
             long ru_majflt;          /* page faults */
             long ru_nswap;           /* swaps */
             long ru_inblock;         /* block input operations */
             long ru_oublock;         /* block output operations */
             long ru_msgsnd;          /* messages sent */
             long ru_msgrcv;          /* messages received */
             long ru_nsignals;        /* signals received */
             long ru_nvcsw;           /* voluntary context switches */
             long ru_nivcsw;          /* involuntary context switches */
     };

     The fields are interpreted as follows:

     ru_utime     the total amount of time spent executing in user mode.

     ru_stime     the total amount of time spent in the system executing on
                  behalf of the process(es).

     ru_maxrss    the maximum resident set size utilized (in kilobytes).

     ru_ixrss     an ``integral'' value indicating the amount of memory used
                  by the text segment that was also shared among other pro-
                  cesses.  This value is expressed in units of kilobytes *
                  ticks-of-execution.

     ru_idrss     an integral value of the amount of unshared memory residing
                  in the data segment of a process (expressed in units of
                  kilobytes * ticks-of-execution).

     ru_isrss     an integral value of the amount of unshared memory residing
                  in the stack segment of a process (expressed in units of
                  kilobytes * ticks-of-execution).

     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 activ-
                  ity.

     ru_nswap     the number of times a process was ``swapped'' out of main
                  memory.

     ru_inblock   the number of times the file system had to perform input.

     ru_oublock   the number of times the file system had to perform output.

     ru_msgsnd    the number of IPC messages sent.

     ru_msgrcv    the number of IPC messages received.

     ru_nsignals  the number of signals delivered.

     ru_nvcsw     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    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.

NOTES
     The numbers ru_inblock and ru_oublock account only for real I/O; data
     supplied by the caching mechanism is charged only to the first process to
     read or write the data.

RETURN VALUES
     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS
     getrusage() will fail if:

     [EINVAL]           The who parameter is not a valid value.

     [EFAULT]           The address specified by the rusage parameter is not
                        in a valid part of the process address space.

SEE ALSO
     clock_gettime(2), gettimeofday(2), wait(2)

STANDARDS
     The getrusage() function conforms to IEEE Std 1003.1-2008 (``POSIX.1'').

     The RUSAGE_THREAD flag is an extension to that specification.

HISTORY
     A predecessor to getrusage(), times(), first appeared in Version 3 AT&T
     UNIX.  The getrusage() system call first appeared in 4.1cBSD.

     The RUSAGE_THREAD flag has been available since OpenBSD 4.8.

BUGS
     There is no way to obtain information about a child process that has not
     yet terminated.

BSD                             March 30, 2017                             BSD