proc.time {base} | R Documentation

## Running Time of R

### Description

`proc.time` determines how much real and CPU time (in seconds) the currently running R process has already taken.

### Usage

    proc.time()

### Details

`proc.time` returns five elements for backwards compatibility, but its `print` method prints a named vector of length 3. The first two entries are the total user and system CPU times of the current R process and any child processes on which it has waited, and the third entry is the ‘real’ elapsed time since the process was started.

### Value

An object of class `"proc_time"` which is a numeric vector of length 5, containing the user, system, and total elapsed times for the currently running R process, and the cumulative sum of user and system times of any child processes spawned by it on which it has waited. (The `print` method combines the child times with those of the main process.)
The definition of ‘user’ and ‘system’ times is from your OS. Typically it is something like
The ‘user time’ is the CPU time charged for the execution of user instructions of the calling process. The ‘system lime’ is the CPU time charged for execution by the system on behalf of the calling process.
The resolution of the times will be system-specific and on Unix-alikes times are rounded to the nearest 1ms. On modern systems they will be that accurate, but on older systems they might be accurate to 1/100 or 1/60 sec.

### Note

It is possible to compile R without support for `proc.time`, when the function will throw an error.

### References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

### See Also

`system.time` for timing a valid R expression, `gc.time` for how much of the time was spent in garbage collection.

### Examples

    ## Not run:
    ## a way to time an R expression: system.time is preferred
    ptm <- proc.time()
    for (i in 1:50) mad(stats::runif(500))
    proc.time() - ptm
    ## End(Not run)

[Package base version 2.7.1 Index]