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

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 ter-
     minated 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 indi-
     cate 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.

BSD
								    May 1, 2010 							       BSD