| 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
Description
Benchmark measurement code.
Synopsis
- initializeTime :: IO ()
- getTime :: IO Double
- getCPUTime :: IO Double
- getCycles :: IO Word64
- getGCStatistics :: IO (Maybe GCStatistics)
- data GCStatistics = GCStatistics {
- gcStatsBytesAllocated :: !Int64
- gcStatsNumGcs :: !Int64
- gcStatsMaxBytesUsed :: !Int64
- gcStatsNumByteUsageSamples :: !Int64
- gcStatsCumulativeBytesUsed :: !Int64
- gcStatsBytesCopied :: !Int64
- gcStatsCurrentBytesUsed :: !Int64
- gcStatsCurrentBytesSlop :: !Int64
- gcStatsMaxBytesSlop :: !Int64
- gcStatsPeakMegabytesAllocated :: !Int64
- gcStatsMutatorCpuSeconds :: !Double
- gcStatsMutatorWallSeconds :: !Double
- gcStatsGcCpuSeconds :: !Double
- gcStatsGcWallSeconds :: !Double
- gcStatsCpuSeconds :: !Double
- gcStatsWallSeconds :: !Double
- secs :: Double -> String
- measure :: Benchmarkable -> Int64 -> IO (Measured, Double)
- runBenchmark :: Benchmarkable -> Double -> IO (Vector Measured, Double)
- runBenchmarkable :: Benchmarkable -> Int64 -> (a -> a -> a) -> (Int64 -> IO () -> IO a) -> IO a
- runBenchmarkable_ :: Benchmarkable -> Int64 -> IO ()
- measured :: Measured
- applyGCStatistics :: Maybe GCStatistics -> Maybe GCStatistics -> Maybe GCStatistics -> Measured -> Measured
- threshold :: Double
Documentation
initializeTime :: IO () Source #
Set up time measurement.
criterion measures time using OS-specific APIs whenever possible for
efficiency. On certain operating systems, such as macOS and Windows, one
must explicitly initialize a timer (which initializeTime accomplishes)
before one can actually measure the current time (which getTime
accomplishes).
It is imperative that you call initializeTime before calling getTime.
(See this bug report for an
example of what can happen if you do not do so.) All of the IO-returning
functions in Criterion.Main make sure that this is done, but other
functions (such as those in Criterion.Measurement) do not guarantee this
unless otherwise stated.
Return the current wallclock time, in seconds since some arbitrary time.
You must call initializeTime once before calling this function!
Refer to the documentation for initializeTime for more details.
getCPUTime :: IO Double Source #
Return the amount of elapsed CPU time, combining user and kernel (system) time into a single measure.
getGCStatistics :: IO (Maybe GCStatistics) Source #
Try to get GC statistics, bearing in mind that the GHC runtime
will throw an exception if statistics collection was not enabled
using "+RTS -T".
If you need guaranteed up-to-date stats, call performGC first.
data GCStatistics Source #
Statistics about memory usage and the garbage collector. Apart from
gcStatsCurrentBytesUsed and gcStatsCurrentBytesSlop all are cumulative values since
the program started.
GCStatistics is cargo-culted from the GCStats data type that GHC.Stats
used to export. Since GCStats was removed in GHC 8.4, criterion uses
GCStatistics to provide a backwards-compatible view of GC statistics.
Constructors
| GCStatistics | |
Fields
| |
Instances
secs :: Double -> String Source #
Convert a number of seconds to a string. The string will consist of four decimal places, followed by a short description of the time units.
Arguments
| :: Benchmarkable | Operation to benchmark. |
| -> Int64 | Number of iterations. |
| -> IO (Measured, Double) |
Measure the execution of a benchmark a given number of times.
This function initializes the timer before measuring time (refer to the
documentation for initializeTime for more details).
Arguments
| :: Benchmarkable | |
| -> Double | Lower bound on how long the benchmarking process should take. In practice, this time limit may be exceeded in order to generate enough data to perform meaningful statistical analyses. |
| -> IO (Vector Measured, Double) |
Run a single benchmark, and return measurements collected while executing it, along with the amount of time the measurement process took.
This function initializes the timer before measuring time (refer to the
documentation for initializeTime for more details).
runBenchmarkable :: Benchmarkable -> Int64 -> (a -> a -> a) -> (Int64 -> IO () -> IO a) -> IO a Source #
runBenchmarkable_ :: Benchmarkable -> Int64 -> IO () Source #
Arguments
| :: Maybe GCStatistics | Statistics gathered at the end of a run, post-GC. |
| -> Maybe GCStatistics | Statistics gathered at the end of a run, pre-GC. |
| -> Maybe GCStatistics | Statistics gathered at the beginning of a run. |
| -> Measured | Value to "modify". |
| -> Measured |
Apply the difference between two sets of GC statistics to a measurement.
The amount of time a benchmark must run for in order for us to have some trust in the raw measurement.
We set this threshold so that we can generate enough data to later perform meaningful statistical analyses.
The threshold is 30 milliseconds. One use of runBenchmark must
accumulate more than 300 milliseconds of total measurements above
this threshold before it will finish.