---
name: "getrusage"
section: "2"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/getrusage"
---

# getrusage(2)

get information about resource utilization

## 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 terminated 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 indicate 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)](/gettimeofday/2.md), [wait(2)](/wait/2.md), [clocks(7)](/clocks/7.md)

## 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.