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-- |
-- Module : Criterion
-- Copyright : (c) 2009, 2010 Bryan O'Sullivan
--
-- License : BSD-style
-- Maintainer : bos@serpentine.com
-- Stability : experimental
-- Portability : GHC
--
-- Core benchmarking code.
module Criterion
(
Benchmarkable(..)
, Benchmark
, Pure
, nf
, whnf
, nfIO
, whnfIO
, bench
, bgroup
, runBenchmark
, runAndAnalyse
) where
import Control.Monad ((<=<), forM_, replicateM_, when)
import Control.Monad.Trans (liftIO)
import Criterion.Analysis (OutlierVariance(..), classifyOutliers,
outlierVariance, noteOutliers)
import Criterion.Config (Config(..), Plot(..), fromLJ)
import Criterion.Environment (Environment(..))
import Criterion.IO (note, prolix, summary)
import Criterion.Measurement (getTime, runForAtLeast, secs, time_)
import Criterion.Monad (Criterion, getConfig, getConfigItem)
import Criterion.Plot (plotWith, plotKDE, plotTiming)
import Criterion.Types (Benchmarkable(..), Benchmark(..), Pure,
bench, bgroup, nf, nfIO, whnf, whnfIO)
import qualified Data.Vector.Unboxed as U
import Statistics.Function (create, minMax)
import Statistics.KernelDensity (epanechnikovPDF)
import Statistics.Resampling (Resample, resample)
import Statistics.Resampling.Bootstrap (Estimate(..), bootstrapBCA)
import Statistics.Sample (mean, stdDev)
import Statistics.Types (Sample)
import System.Random.MWC (withSystemRandom)
import System.Mem (performGC)
import Text.Printf (printf)
-- | Run a single benchmark, and return timings measured when
-- executing it.
runBenchmark :: Benchmarkable b => Environment -> b -> Criterion Sample
runBenchmark env b = do
_ <- liftIO $ runForAtLeast 0.1 10000 (`replicateM_` getTime)
let minTime = envClockResolution env * 1000
(testTime, testIters, _) <- liftIO $ runForAtLeast (min minTime 0.1) 1 (run b)
_ <- prolix "ran %d iterations in %s\n" testIters (secs testTime)
cfg <- getConfig
let newIters = ceiling $ minTime * testItersD / testTime
sampleCount = fromLJ cfgSamples cfg
newItersD = fromIntegral newIters
testItersD = fromIntegral testIters
_ <- note "collecting %d samples, %d iterations each, in estimated %s\n"
sampleCount newIters (secs (fromIntegral sampleCount * newItersD *
testTime / testItersD))
times <- liftIO . fmap (U.map ((/ newItersD) . subtract (envClockCost env))) .
create sampleCount . const $ do
when (fromLJ cfgPerformGC cfg) $ performGC
time_ (run b newIters)
return times
-- | Run a single benchmark and analyse its performance.
runAndAnalyseOne :: Benchmarkable b => Environment -> String -> b
-> Criterion Sample
runAndAnalyseOne env _desc b = do
times <- runBenchmark env b
let numSamples = U.length times
let ests = [mean,stdDev]
numResamples <- getConfigItem $ fromLJ cfgResamples
_ <- note "bootstrapping with %d resamples\n" numResamples
res <- liftIO . withSystemRandom $ \gen ->
resample gen ests numResamples times :: IO [Resample]
ci <- getConfigItem $ fromLJ cfgConfInterval
let [em,es] = bootstrapBCA ci times ests res
(effect, v) = outlierVariance em es (fromIntegral $ numSamples)
wibble = case effect of
Unaffected -> "unaffected" :: String
Slight -> "slightly inflated"
Moderate -> "moderately inflated"
Severe -> "severely inflated"
bs "mean" em
summary ","
bs "std dev" es
summary "\n"
noteOutliers (classifyOutliers times)
_ <- note "variance introduced by outliers: %.3f%%\n" (v * 100)
_ <- note "variance is %s by outliers\n" wibble
return times
where bs :: String -> Estimate -> Criterion ()
bs d e = do _ <- note "%s: %s, lb %s, ub %s, ci %.3f\n" d
(secs $ estPoint e)
(secs $ estLowerBound e) (secs $ estUpperBound e)
(estConfidenceLevel e)
summary $ printf "%g,%g,%g"
(estPoint e)
(estLowerBound e) (estUpperBound e)
plotAll :: [(String, Sample)] -> Criterion ()
plotAll descTimes = forM_ descTimes $ \(desc,times) -> do
plotWith Timing $ \o -> plotTiming o desc times
plotWith KernelDensity $ \o -> uncurry (plotKDE o desc extremes)
(epanechnikovPDF 100 times)
where
extremes = case descTimes of
(_:_:_) -> toJust . minMax . concatU . map snd $ descTimes
_ -> Nothing
concatU = foldr (U.++) U.empty
toJust r@(lo, hi)
| lo == infinity || hi == -infinity = Nothing
| otherwise = Just r
where infinity = 1/0
-- | Run, and analyse, one or more benchmarks.
runAndAnalyse :: (String -> Bool) -- ^ A predicate that chooses
-- whether to run a benchmark by its
-- name.
-> Environment
-> Benchmark
-> Criterion ()
runAndAnalyse p env = plotAll <=< go ""
where go pfx (Benchmark desc b)
| p desc' = do _ <- note "\nbenchmarking %s\n" desc'
summary (show desc' ++ ",") -- String will be quoted
x <- runAndAnalyseOne env desc' b
sameAxis <- getConfigItem $ fromLJ cfgPlotSameAxis
if sameAxis
then return [(desc',x)]
else plotAll [(desc',x)] >> return []
| otherwise = return []
where desc' = prefix pfx desc
go pfx (BenchGroup desc bs) =
concat `fmap` mapM (go (prefix pfx desc)) bs
prefix "" desc = desc
prefix pfx desc = pfx ++ '/' : desc
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