Copyright (c) 1980 Regents of the University of California.
All rights reserved. The Berkeley software License Agreement
specifies the terms and conditions for redistribution.

@(#)getrusage.2 6.3 (Berkeley) 08/26/85

C 4 getrusage - get information about resource utilization

#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;

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 */
 int ru_maxrss;
 int ru_ixrss; /* integral shared memory size */
 int ru_idrss; /* integral unshared data size */
 int ru_isrss; /* integral unshared stack size */
 int ru_minflt; /* page reclaims */
 int ru_majflt; /* page faults */
 int ru_nswap; /* swaps */
 int ru_inblock; /* block input operations */
 int ru_oublock; /* block output operations */
 int ru_msgsnd; /* messages sent */
 int ru_msgrcv; /* messages received */
 int ru_nsignals; /* signals received */
 int ru_nvcsw; /* voluntary context switches */
 int ru_nivcsw; /* involuntary context switches */
};

The fields are interpreted as follows:

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

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

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

15 ru_ixrss an \*(lqintegral\*(rq value indicating the amount of memory used that 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.

15 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).

15 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).

15 ru_minflt the number of page faults serviced without any i/o activity; here i/o activity is avoided by \*(lqreclaiming\*(rq a page frame from the list of pages awaiting reallocation.

15 ru_majflt the number of page faults serviced that required i/o activity.

15 ru_nswap the number of times a process was \*(lqswapped\*(rq out of main memory.

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

15 ru_outblock the number of times the file system had to perform output.

15 ru_msgsnd the number of ipc messages sent.

15 ru_msgrcv the number of ipc messages received.

15 ru_nsignals the number of signals delivered.

15 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).

15 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.

The numbers ru_inblock and ru_outblock account only for real i/o; data supplied by the cacheing mechanism is charged only to the first process to read or write the data. The possible errors for getrusage are:

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

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

gettimeofday(2), wait(2) There is no way to obtain information about a child process that has not yet terminated.