GETRUSAGE(2)

NAME
getrusage - get information about resource utilization

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

#define	RUSAGE_SELF	0	/* calling process */
#define	RUSAGE_CHILDREN	-1	/* terminated child processes */

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

DESCRIPTION
Getrusage returns information describing the resources utilized by the current process, or all its terminated child processes. The who parameter is one of RUSAGE_SELF and RUSAGE_CHILDREN. If rusage is non-zero, the buffer it points to 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;
    	/* NEXT THREE VALUES NOT COMPUTED IN DYNIX (always returned as 0) */
    	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 */
    };

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 pages, as defined by getpagesize(2)).

ru_ixrss
    an “integral” value indicating the amount of memory used which was also shared among other processes. This value is expressed in units of kilobytes * seconds-of-execution and is calculated by summing the number of shared memory pages in use each time the internal system clock ticks and then averaging over 1 second intervals. Not computed in DYNIX; always returns as 0.

ru_idrss
    an integral value of the amount of unshared memory residing in the data segment of a process (expressed in units of kilobytes * seconds-of-execution). Not computed in DYNIX; always returns as 0.

ru_isrss
    an integral value of the amount of unshared memory residing in the stack segment of a process (expressed in units of kilobytes * seconds-of-execution). Not computed in DYNIX; always returns as 0.

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 which 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_outblock
    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_outblock 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.

ERRORS

[EFAULT]
    The memory pointed to by rusage lies outside the valid address space for the process.

SEE ALSO
gettimeofday(2), wait(2)

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

Due to the multi-processing nature of DYNIX, it is possible for the CPU time (user + system time) for a child process to greatly exceed the elapsed real time. This is especially true if the child process forks and waits for children of its own.