NAME

       getrusage — get information about resource utilization

LIBRARY

       Standard C Library (libc, -lc)

SYNOPSIS

       #include <sys/types.h>
       #include <sys/time.h>
       #include <sys/resource.h>
       #define    RUSAGE_SELF      0
       #define    RUSAGE_CHILDREN -1
       #define    RUSAGE_THREAD   1

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

DESCRIPTION

       The  getrusage() system call returns information describing the resources utilized by the current thread,
       the current process, or all its terminated child processes.  The who argument  is  either  RUSAGE_THREAD,
       RUSAGE_SELF,  or RUSAGE_CHILDREN.  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  processes.   This value is expressed in units of kilobytes * ticks-of-
                    execution.  Ticks are statistics clock ticks.  The  statistics  clock  has  a  frequency  of
                    sysconf(_SC_CLK_TCK) ticks per second.

       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 activity.

       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

       The  getrusage()  function  returns the value 0 if successful; otherwise the value -1 is returned and the
       global variable errno is set to indicate the error.

ERRORS

       The getrusage() system call will fail if:

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

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

SEE ALSO

       gettimeofday(2), wait(2), clocks(7)

HISTORY

       The  getrusage()  system  call  appeared  in  4.2BSD.   The  RUSAGE_THREAD  facility  first  appeared  in
       FreeBSD 8.1.

BUGS

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

Debian                                             May 1, 2010                                      GETRUSAGE(2)