GETRUSAGE

Section: System Calls (2)
Updated: April 3, 1987
Index Return to Main Contents

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 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 */
        int     ru_maxrss;
        int     ru_ixrss;               /* integral shared text 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:

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.
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.

ERRORS

The possible errors for getrusage are:

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

BUGS

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

This document was created by man2html, using the manual pages.
Time: 04:51:40 GMT, January 31, 2023