Criterion.Measurement.Types

criterion-measurement-0.2.3.0: Criterion measurement functionality and associated types

Copyright | (c) 2009-2014 Bryan O'Sullivan
License | BSD-style
Maintainer | bos@serpentine.com
Stability | experimental
Portability | GHC
Safe Haskell | Trustworthy
Language | Haskell2010

Criterion.Measurement.Types

Contents

- Benchmark descriptions
- Measurements
- Benchmark construction
  - Evaluation control

Description

Types for benchmarking.

The core type is `Benchmarkable`, which admits both pure functions and `IO` actions.

For a pure function of type `a -> b`, the benchmarking harness calls this function repeatedly, each time with a different `Int64` argument (the number of times to run the function in a loop), and reduces the result the function returns to weak head normal form.

For an action of type `IO a`, the benchmarking harness calls the action repeatedly, but does not reduce the result.

Synopsis

- data Benchmarkable = NFData a => Benchmarkable {
  - allocEnv :: Int64 -> IO a
  - cleanEnv :: Int64 -> a -> IO ()
  - runRepeatedly :: a -> Int64 -> IO ()
  - perRun :: Bool
  }
- data Benchmark where
  - Environment :: forall env a. NFData env => IO env -> (env -> IO a) -> (env -> Benchmark) -> Benchmark
  - Benchmark :: String -> Benchmarkable -> Benchmark
  - BenchGroup :: String -> [Benchmark] -> Benchmark
- data Measured = Measured {
  - measTime :: !Double
  - measCpuTime :: !Double
  - measCycles :: !Int64
  - measIters :: !Int64
  - measAllocated :: !Int64
  - measPeakMbAllocated :: !Int64
  - measNumGcs :: !Int64
  - measBytesCopied :: !Int64
  - measMutatorWallSeconds :: !Double
  - measMutatorCpuSeconds :: !Double
  - measGcWallSeconds :: !Double
  - measGcCpuSeconds :: !Double
  }
- fromInt :: Int64 -> Maybe Int64
- toInt :: Maybe Int64 -> Int64
- fromDouble :: Double -> Maybe Double
- toDouble :: Maybe Double -> Double
- measureAccessors :: Map String (Measured -> Maybe Double, String)
- measureKeys :: [String]
- measure :: Unbox a => (Measured -> a) -> Vector Measured -> Vector a
- rescale :: Measured -> Measured
- env :: NFData env => IO env -> (env -> Benchmark) -> Benchmark
- envWithCleanup :: NFData env => IO env -> (env -> IO a) -> (env -> Benchmark) -> Benchmark
- perBatchEnv :: (NFData env, NFData b) => (Int64 -> IO env) -> (env -> IO b) -> Benchmarkable
- perBatchEnvWithCleanup :: (NFData env, NFData b) => (Int64 -> IO env) -> (Int64 -> env -> IO ()) -> (env -> IO b) -> Benchmarkable
- perRunEnv :: (NFData env, NFData b) => IO env -> (env -> IO b) -> Benchmarkable
- perRunEnvWithCleanup :: (NFData env, NFData b) => IO env -> (env -> IO ()) -> (env -> IO b) -> Benchmarkable
- toBenchmarkable :: (Int64 -> IO ()) -> Benchmarkable
- bench :: String -> Benchmarkable -> Benchmark
- bgroup :: String -> [Benchmark] -> Benchmark
- addPrefix :: String -> String -> String
- benchNames :: Benchmark -> [String]
- nf :: NFData b => (a -> b) -> a -> Benchmarkable
- whnf :: (a -> b) -> a -> Benchmarkable
- nfIO :: NFData a => IO a -> Benchmarkable
- whnfIO :: IO a -> Benchmarkable
- nfAppIO :: NFData b => (a -> IO b) -> a -> Benchmarkable
- whnfAppIO :: (a -> IO b) -> a -> Benchmarkable

# Benchmark descriptions

data Benchmarkable #

A pure function or impure action that can be benchmarked. The `Int64` parameter indicates the number of times to run the given function or action.

Constructors

NFData a => Benchmarkable |
Fields allocEnv :: Int64 -> IO a cleanEnv :: Int64 -> a -> IO () runRepeatedly :: a -> Int64 -> IO () perRun :: Bool

data Benchmark where #

Specification of a collection of benchmarks and environments. A benchmark may consist of:

- An environment that creates input data for benchmarks, created with `env`.
- A single `Benchmarkable` item with a name, created with `bench`.
- A (possibly nested) group of `Benchmark`s, created with `bgroup`.

Constructors

Environment :: forall env a. NFData env => IO env -> (env -> IO a) -> (env -> Benchmark) -> Benchmark |
Benchmark :: String -> Benchmarkable -> Benchmark |
BenchGroup :: String -> [Benchmark] -> Benchmark |

#### Instances

Instances details

Show Benchmark # |
Instance details Defined in Criterion.Measurement.Types Methods showsPrec :: Int -> Benchmark -> ShowS # show :: Benchmark -> String # showList :: [Benchmark] -> ShowS #

# Measurements

data Measured #

A collection of measurements made while benchmarking.

Measurements related to garbage collection are tagged with GC. They will only be available if a benchmark is run with `"+RTS -T"`.

Packed storage. When GC statistics cannot be collected, GC values will be set to huge negative values. If a field is labeled with "GC" below, use `fromInt` and `fromDouble` to safely convert to "real" values.

Constructors

Measured |
Fields measTime :: !Double Total wall-clock time elapsed, in seconds. measCpuTime :: !Double Total CPU time elapsed, in seconds. Includes both user and kernel (system) time. measCycles :: !Int64 Cycles, in unspecified units that may be CPU cycles. (On i386 and x86_64, this is measured using the `rdtsc` instruction.) measIters :: !Int64 Number of loop iterations measured. measAllocated :: !Int64 (GC) Number of bytes allocated. Access using `fromInt`. measPeakMbAllocated :: !Int64 (GC) Max number of megabytes allocated. Access using `fromInt`. measNumGcs :: !Int64 (GC) Number of garbage collections performed. Access using `fromInt`. measBytesCopied :: !Int64 (GC) Number of bytes copied during garbage collection. Access using `fromInt`. measMutatorWallSeconds :: !Double (GC) Wall-clock time spent doing real work ("mutation"), as distinct from garbage collection. Access using `fromDouble`. measMutatorCpuSeconds :: !Double (GC) CPU time spent doing real work ("mutation"), as distinct from garbage collection. Access using `fromDouble`. measGcWallSeconds :: !Double (GC) Wall-clock time spent doing garbage collection. Access using `fromDouble`. measGcCpuSeconds :: !Double (GC) CPU time spent doing garbage collection. Access using `fromDouble`.

#### Instances

Instances details

FromJSON Measured # |
Instance details Defined in Criterion.Measurement.Types Methods parseJSON :: Value -> Parser Measured # parseJSONList :: Value -> Parser [Measured] # omittedField :: Maybe Measured #
ToJSON Measured # |
Instance details Defined in Criterion.Measurement.Types Methods toJSON :: Measured -> Value # toEncoding :: Measured -> Encoding # toJSONList :: [Measured] -> Value # toEncodingList :: [Measured] -> Encoding # omitField :: Measured -> Bool #
Binary Measured # |
Instance details Defined in Criterion.Measurement.Types Methods put :: Measured -> Put # get :: Get Measured # putList :: [Measured] -> Put #
NFData Measured # |
Instance details Defined in Criterion.Measurement.Types Methods rnf :: Measured -> () #
Data Measured # |
Instance details Defined in Criterion.Measurement.Types Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Measured -> c Measured # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Measured # toConstr :: Measured -> Constr # dataTypeOf :: Measured -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Measured) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Measured) # gmapT :: (forall b. Data b => b -> b) -> Measured -> Measured # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Measured -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Measured -> r # gmapQ :: (forall d. Data d => d -> u) -> Measured -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Measured -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Measured -> m Measured # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Measured -> m Measured # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Measured -> m Measured #
Generic Measured # |
Instance details Defined in Criterion.Measurement.Types Associated Types
type Rep Measured |
Instance details Defined in Criterion.Measurement.Types type Rep Measured = D1 ('MetaData "Measured" "Criterion.Measurement.Types" "criterion-measurement-0.2.3.0-GICzKqVZCZFbK3A27iKbD" 'False) (C1 ('MetaCons "Measured" 'PrefixI 'True) (((S1 ('MetaSel ('Just "measTime") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double) :*: (S1 ('MetaSel ('Just "measCpuTime") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double) :*: S1 ('MetaSel ('Just "measCycles") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64))) :*: (S1 ('MetaSel ('Just "measIters") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64) :*: (S1 ('MetaSel ('Just "measAllocated") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64) :*: S1 ('MetaSel ('Just "measPeakMbAllocated") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64)))) :*: ((S1 ('MetaSel ('Just "measNumGcs") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64) :*: (S1 ('MetaSel ('Just "measBytesCopied") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64) :*: S1 ('MetaSel ('Just "measMutatorWallSeconds") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double))) :*: (S1 ('MetaSel ('Just "measMutatorCpuSeconds") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double) :*: (S1 ('MetaSel ('Just "measGcWallSeconds") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double) :*: S1 ('MetaSel ('Just "measGcCpuSeconds") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double))))))
Methods from :: Measured -> Rep Measured x # to :: Rep Measured x -> Measured #
Read Measured # |
Instance details Defined in Criterion.Measurement.Types Methods readsPrec :: Int -> ReadS Measured # readList :: ReadS [Measured] # readPrec :: ReadPrec Measured # readListPrec :: ReadPrec [Measured] #
Show Measured # |
Instance details Defined in Criterion.Measurement.Types Methods showsPrec :: Int -> Measured -> ShowS # show :: Measured -> String # showList :: [Measured] -> ShowS #
Eq Measured # |
Instance details Defined in Criterion.Measurement.Types Methods (==) :: Measured -> Measured -> Bool # (/=) :: Measured -> Measured -> Bool #
type Rep Measured # |
Instance details Defined in Criterion.Measurement.Types type Rep Measured = D1 ('MetaData "Measured" "Criterion.Measurement.Types" "criterion-measurement-0.2.3.0-GICzKqVZCZFbK3A27iKbD" 'False) (C1 ('MetaCons "Measured" 'PrefixI 'True) (((S1 ('MetaSel ('Just "measTime") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double) :*: (S1 ('MetaSel ('Just "measCpuTime") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double) :*: S1 ('MetaSel ('Just "measCycles") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64))) :*: (S1 ('MetaSel ('Just "measIters") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64) :*: (S1 ('MetaSel ('Just "measAllocated") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64) :*: S1 ('MetaSel ('Just "measPeakMbAllocated") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64)))) :*: ((S1 ('MetaSel ('Just "measNumGcs") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64) :*: (S1 ('MetaSel ('Just "measBytesCopied") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Int64) :*: S1 ('MetaSel ('Just "measMutatorWallSeconds") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double))) :*: (S1 ('MetaSel ('Just "measMutatorCpuSeconds") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double) :*: (S1 ('MetaSel ('Just "measGcWallSeconds") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double) :*: S1 ('MetaSel ('Just "measGcCpuSeconds") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Double))))))

fromInt :: Int64 -> Maybe Int64 #

Convert a (possibly unavailable) GC measurement to a true value. If the measurement is a huge negative number that corresponds to "no data", this will return `Nothing`.

toInt :: Maybe Int64 -> Int64 #

Convert from a true value back to the packed representation used for GC measurements.

fromDouble :: Double -> Maybe Double #

Convert a (possibly unavailable) GC measurement to a true value. If the measurement is a huge negative number that corresponds to "no data", this will return `Nothing`.

toDouble :: Maybe Double -> Double #

Convert from a true value back to the packed representation used for GC measurements.

measureAccessors :: Map String (Measured -> Maybe Double, String) #

Field names and accessors for a `Measured` record.

measureKeys :: [String] #

Field names in a `Measured` record, in the order in which they appear.

measure :: Unbox a => (Measured -> a) -> Vector Measured -> Vector a #

rescale :: Measured -> Measured #

Normalise every measurement as if `measIters` was 1.

(`measIters` itself is left unaffected.)

# Benchmark construction

env #

Arguments

:: NFData env |
=> IO env | Create the environment. The environment will be evaluated to normal form before being passed to the benchmark.
-> (env -> Benchmark) | Take the newly created environment and make it available to the given benchmarks.
-> Benchmark |

Run a benchmark (or collection of benchmarks) in the given environment. The purpose of an environment is to lazily create input data to pass to the functions that will be benchmarked.

A common example of environment data is input that is read from a file. Another is a large data structure constructed in-place.

Motivation. In earlier versions of criterion, all benchmark inputs were always created when a program started running. By deferring the creation of an environment when its associated benchmarks need the its, we avoid two problems that this strategy caused:

- Memory pressure distorted the results of unrelated benchmarks. If one benchmark needed e.g. a gigabyte-sized input, it would force the garbage collector to do extra work when running some other benchmark that had no use for that input. Since the data created by an environment is only available when it is in scope, it should be garbage collected before other benchmarks are run.
- The time cost of generating all needed inputs could be significant in cases where no inputs (or just a few) were really needed. This occurred often, for instance when just one out of a large suite of benchmarks was run, or when a user would list the collection of benchmarks without running any.

Creation. An environment is created right before its related benchmarks are run. The `IO` action that creates the environment is run, then the newly created environment is evaluated to normal form (hence the `NFData` constraint) before being passed to the function that receives the environment.

Complex environments. If you need to create an environment that contains multiple values, simply pack the values into a tuple.

Lazy pattern matching. In situations where a "real" environment is not needed, e.g. if a list of benchmark names is being generated, a value which throws an exception will be passed to the function that receives the environment. This avoids the overhead of generating an environment that will not actually be used.

The function that receives the environment must use lazy pattern matching to deconstruct the tuple (e.g., `~(x, y)`, not `(x, y)`), as use of strict pattern matching will cause a crash if an exception-throwing value is passed in.

Example. This program runs benchmarks in an environment that contains two values. The first value is the contents of a text file; the second is a string. Pay attention to the use of a lazy pattern to deconstruct the tuple in the function that returns the benchmarks to be run.

    setupEnv = do
      let small = replicate 1000 (1 :: Int)
      big <- map length . words <$> readFile "/usr/dict/words"
      return (small, big)

    main = defaultMain [
       -- notice the lazy pattern match here!
       env setupEnv $ \ ~(small,big) -> bgroup "main" [
       bgroup "small" [
         bench "length" $ whnf length small
       , bench "length . filter" $ whnf (length . filter (==1)) small
       ]
     ,  bgroup "big" [
         bench "length" $ whnf length big
       , bench "length . filter" $ whnf (length . filter (==1)) big
       ]
     ] ]

Discussion. The environment created in the example above is intentionally not ideal. As Haskell's scoping rules suggest, the variable `big` is in scope for the benchmarks that use only `small`. It would be better to create a separate environment for `big`, so that it will not be kept alive while the unrelated benchmarks are being run.

envWithCleanup #

Arguments

:: NFData env |
=> IO env | Create the environment. The environment will be evaluated to normal form before being passed to the benchmark.
-> (env -> IO a) | Clean up the created environment.
-> (env -> Benchmark) | Take the newly created environment and make it available to the given benchmarks.
-> Benchmark |

Same as `env`, but but allows for an additional callback to clean up the environment. Resource clean up is exception safe, that is, it runs even if the `Benchmark` throws an exception.

perBatchEnv #

Arguments

:: (NFData env, NFData b) |
=> (Int64 -> IO env) | Create an environment for a batch of N runs. The environment will be evaluated to normal form before running.
-> (env -> IO b) | Function returning the IO action that should be benchmarked with the newly generated environment.
-> Benchmarkable |

Create a Benchmarkable where a fresh environment is allocated for every batch of runs of the benchmarkable.

The environment is evaluated to normal form before the benchmark is run.

When using `whnf`, `whnfIO`, etc. Criterion creates a `Benchmarkable` whichs runs a batch of `N` repeat runs of that expressions. Criterion may run any number of these batches to get accurate measurements. Environments created by `env` and `envWithCleanup`, are shared across all these batches of runs.

This is fine for simple benchmarks on static input, but when benchmarking IO operations where these operations can modify (and especially grow) the environment this means that later batches might have their accuracy effected due to longer, for example, longer garbage collection pauses.

An example: Suppose we want to benchmark writing to a Chan, if we allocate the Chan using environment and our benchmark consists of `writeChan env ()`, the contents and thus size of the Chan will grow with every repeat. If Criterion runs a 1,000 batches of 1,000 repeats, the result is that the channel will have 999,000 items in it by the time the last batch is run. Since GHC GC has to copy the live set for every major GC this means our last set of writes will suffer a lot of noise of the previous repeats.

By allocating a fresh environment for every batch of runs this function should eliminate this effect.

perBatchEnvWithCleanup #

Arguments

:: (NFData env, NFData b) |
=> (Int64 -> IO env) | Create an environment for a batch of N runs. The environment will be evaluated to normal form before running.
-> (Int64 -> env -> IO ()) | Clean up the created environment.
-> (env -> IO b) | Function returning the IO action that should be benchmarked with the newly generated environment.
-> Benchmarkable |

Same as `perBatchEnv`, but but allows for an additional callback to clean up the environment. Resource clean up is exception safe, that is, it runs even if the `Benchmark` throws an exception.

perRunEnv #

Arguments

:: (NFData env, NFData b) |
=> IO env | Action that creates the environment for a single run.
-> (env -> IO b) | Function returning the IO action that should be benchmarked with the newly generated environment.
-> Benchmarkable |

Create a Benchmarkable where a fresh environment is allocated for every run of the operation to benchmark. This is useful for benchmarking mutable operations that need a fresh environment, such as sorting a mutable Vector.

As with `env` and `perBatchEnv` the environment is evaluated to normal form before the benchmark is run.

This introduces extra noise and result in reduce accuracy compared to other Criterion benchmarks. But allows easier benchmarking for mutable operations than was previously possible.

perRunEnvWithCleanup #

Arguments

:: (NFData env, NFData b) |
=> IO env | Action that creates the environment for a single run.
-> (env -> IO ()) | Clean up the created environment.
-> (env -> IO b) | Function returning the IO action that should be benchmarked with the newly generated environment.
-> Benchmarkable |

Same as `perRunEnv`, but but allows for an additional callback to clean up the environment. Resource clean up is exception safe, that is, it runs even if the `Benchmark` throws an exception.

toBenchmarkable :: (Int64 -> IO ()) -> Benchmarkable #

Construct a `Benchmarkable` value from an impure action, where the `Int64` parameter indicates the number of times to run the action.

bench #

Arguments

:: String | A name to identify the benchmark.
-> Benchmarkable | An activity to be benchmarked.
-> Benchmark |

Create a single benchmark.

bgroup #

Arguments

:: String | A name to identify the group of benchmarks.
-> [Benchmark] | Benchmarks to group under this name.
-> Benchmark |

Group several benchmarks together under a common name.

addPrefix #

Arguments

:: String | Prefix.
-> String | Name.
-> String |

Add the given prefix to a name. If the prefix is empty, the name is returned unmodified. Otherwise, the prefix and name are separated by a `'/'` character.

benchNames :: Benchmark -> [String] #

Retrieve the names of all benchmarks. Grouped benchmarks are prefixed with the name of the group they're in.

## Evaluation control

nf :: NFData b => (a -> b) -> a -> Benchmarkable #

Apply an argument to a function, and evaluate the result to normal form (NF).

whnf :: (a -> b) -> a -> Benchmarkable #

Apply an argument to a function, and evaluate the result to weak head normal form (WHNF).

nfIO :: NFData a => IO a -> Benchmarkable #

Perform an action, then evaluate its result to normal form (NF). This is particularly useful for forcing a lazy `IO` action to be completely performed.

If the construction of the 'IO a' value is an important factor in the benchmark, it is best to use `nfAppIO` instead.

whnfIO :: IO a -> Benchmarkable #

Perform an action, then evaluate its result to weak head normal form (WHNF). This is useful for forcing an `IO` action whose result is an expression to be evaluated down to a more useful value.

If the construction of the 'IO a' value is an important factor in the benchmark, it is best to use `whnfAppIO` instead.

nfAppIO :: NFData b => (a -> IO b) -> a -> Benchmarkable #

Apply an argument to a function which performs an action, then evaluate its result to normal form (NF). This function constructs the 'IO b' value on each iteration, similar to `nf`. This is particularly useful for `IO` actions where the bulk of the work is not bound by IO, but by pure computations that may optimize away if the argument is known statically, as in `nfIO`.

whnfAppIO :: (a -> IO b) -> a -> Benchmarkable #

Perform an action, then evaluate its result to weak head normal form (WHNF). This function constructs the 'IO b' value on each iteration, similar to `whnf`. This is particularly useful for `IO` actions where the bulk of the work is not bound by IO, but by pure computations that may optimize away if the argument is known statically, as in `nfIO`.