| proc.time {base} | R Documentation |
proc.time determines how much real and CPU time (in seconds)
the currently running R process has already taken.
proc.time()
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.
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 time’ 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.
It is possible to compile R without support for proc.time,
when the function will throw an error.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
system.time for timing a valid R expression,
gc.time for how much of the time was spent in garbage
collection.
## 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)