June 4, 1993 GETRUSAGE 2

### NAME

getrusage - get information about resource utilization

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

#define RUSAGE_SELF 0
#define RUSAGE_CHILDREN -1
```int` getrusage(```int who``, struct rusage *rusage`)

### DESCRIPTION

getrusage(``) returns information describing the resources used by the current process, or all its terminated child processes. The ```who` parameter is either ```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 used (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

getrusage(``) returns -1 on error. The possible errors 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.

### SEE ALSO

gettimeofday(2), wait(2)

### HISTORY

The getrusage(``) function call appeared in 4.2BSD.

### BUGS

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