papi.flips <- function(expr)
{
papi.check.ncounters(3L)
ret <- .Call(papi_flips_on)
if (ret == -1L)
stop("PAPI failed to initialize hardware counters.\nYour platform may not support floating point operation event.\n")
eval(expr)
ret <- .Call(papi_flips_off)
if (is.integer(ret) && ret == -1L)
stop("There was a problem recovering the counter information.")
return( ret )
}
#' flips
#'
#' Measuring floating point instructions.
#'
#' This function measures the evaluation of the provided expression, expr, for
#' real time, process time, number of floating point instructions, and floating
#' point instruction rate. The additional arguments, gcFirst and burnin, can be
#' toggled to better simulate the target context.
#'
#' @param expr
#' A valid R expression to be profiled.
#' @param gcFirst
#' logical; determines if garbage collection should be called
#' before profiling.
#' @param burnin
#' logical; determines if the function should first be evaluated
#' with an empty expression.
#'
#' @return
#' The return is a list consisting of:
#' \tabular{ll}{
#' \code{real_time} \tab real time spent evaluating expression \cr
#' \code{proc_time} \tab total process time spent evaluating expression \cr
#' \code{flpins} \tab FLoating Point INStructions (count) \cr
#' \code{mflips} \tab Mflips (flpins per second) \cr
#' }
#'
#' @keywords programming
#'
#' @examples
#' \dontrun{
#' library(pbdPAPI)
#'
#' system.flips(1+1)
#' }
#'
#' @export
system.flips <- function(expr, gcFirst=TRUE, burnin=TRUE)
{
if (burnin)
b <- system.flips(gcFirst=gcFirst, burnin=FALSE)
if (gcFirst)
invisible(gc(FALSE))
if (missing(expr))
expr <- NULL
events <- "PAPI_FP_INS"
papi.avail.lookup(events=events, shorthand=FALSE)
ret <- papi.flips(expr=expr)
if (burnin)
{
for (i in 3:length(ret))
ret[[i]] <- max(ret[[i]] - b[[i]], 0)
}
return( ret )
}
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