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       getrusage - get resource usage


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

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


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

              Return resource usage statistics for the calling process,  which
              is the sum of resources used by all threads in the process.

              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  resource usages are returned in the structure pointed to by usage,
       which has the following form:

           struct rusage {
               struct timeval ru_utime; /* user time used */
               struct timeval ru_stime; /* system 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 */
               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 */


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


       EFAULT usage points outside the accessible address space.

       EINVAL who is invalid.


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

       RUSAGE_THREAD is Linux-specific.


       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  non-conformance
       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.  Not all fields are meaningful under Linux.  In Linux  2.4
       only  the  fields  ru_utime,  ru_stime,  ru_minflt,  and  ru_majflt are
       maintained.   Since  Linux  2.6,  ru_nvcsw  and  ru_nivcsw   are   also

       See also the description of /proc/PID/stat in proc(5).


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


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