allocation test

alloc_test.fs

open System

// returns: median value of a list
let inline median input = 
    let sorted = input |> Seq.toArray |> Array.sort
    let m1,m2 = 
        let len = sorted.Length-1 |> float
        len/2. |> floor |> int, len/2. |> ceil |> int 
    (sorted.[m1] + sorted.[m2] |> float)/2.


// n: allocate a (n * n) array at once
// x: fill the array with this
// returns: milliseconds to do all allocations
let medianAllocateTime numTrials numTimes n x =
    let mutable results = []
    for attempt in 1 .. numTrials do
        printf "."
        let stopWatch = System.Diagnostics.Stopwatch.StartNew()
        for i in 1 .. numTimes do
            Array2D.init n n (fun x y -> x) |> ignore
        stopWatch.Stop()
        results <- stopWatch.Elapsed.TotalMilliseconds::results
    median results

[<EntryPoint>]
let main argv =
    let numTrials = 100
    let numTimes = 1000
    let blank = String.replicate (numTrials - 20) " "
    let banner = String.replicate numTrials "="
    printfn "Testing with %d allocations..." numTimes
    printfn "%s" banner
    printfn "\r 1KiB   (16*16 *  4) = %.2fms%s" (medianAllocateTime numTrials numTimes 16 0s) blank
    printfn "\r 2KiB   (16*16 *  8) = %.2fms%s" (medianAllocateTime numTrials numTimes 16 0) blank
    printfn "\r 4KiB   (16*16 * 16) = %.2fms%s" (medianAllocateTime numTrials numTimes 16 0L) blank
    printfn "%s" banner
    printfn "\r 4KiB   (32*32 *  4) = %.2fms%s" (medianAllocateTime numTrials numTimes 32 0s) blank
    printfn "\r 8KiB   (32*32 *  8) = %.2fms%s" (medianAllocateTime numTrials numTimes 32 0) blank
    printfn "\r 16KiB  (32*32 * 16) = %.2fms%s" (medianAllocateTime numTrials numTimes 32 0L) blank
    printfn "%s" banner
    printfn "\r 16KiB  (64*64 *  4) = %.2fms%s" (medianAllocateTime numTrials numTimes 64 0s) blank
    printfn "\r 32KiB  (64*64 *  8) = %.2fms%s" (medianAllocateTime numTrials numTimes 64 0) blank
    printfn "\r 64KiB  (64*64 * 16) = %.2fms%s" (medianAllocateTime numTrials numTimes 64 0L) blank
    printfn "%s" banner
    printfn "\r 64KiB  (128*128 *  4) = %.2fms%s" (medianAllocateTime numTrials numTimes 128 0s) blank
    printfn "\r 128KiB (128*128 *  8) = %.2fms%s" (medianAllocateTime numTrials numTimes 128 0) blank
    printfn "\r 256KiB (128*128 * 16) = %.2fms%s" (medianAllocateTime numTrials numTimes 128 0L) blank
    printfn "%s" banner
    printfn "\r 256KiB (128*128 *  4) = %.2fms%s" (medianAllocateTime numTrials numTimes 256 0s) blank
    printfn "\r 512KiB (128*128 *  8) = %.2fms%s" (medianAllocateTime numTrials numTimes 256 0) blank
    printfn "\r 1MiB   (128*128 * 16) = %.2fms%s" (medianAllocateTime numTrials numTimes 256 0L) blank
    printfn "Done."
    Console.ReadKey() |> ignore
    0

results.txt

Testing with 1000 allocations...
====================================================================================================
 1KiB   (16*16 *  4) = 4.42ms
 2KiB   (16*16 *  8) = 4.10ms
 4KiB   (16*16 * 16) = 3.65ms
====================================================================================================
 4KiB   (32*32 *  4) = 9.29ms
 8KiB   (32*32 *  8) = 9.98ms
 16KiB  (32*32 * 16) = 10.39ms
====================================================================================================
 16KiB  (64*64 *  4) = 33.32ms
 32KiB  (64*64 *  8) = 33.28ms
 64KiB  (64*64 * 16) = 33.20ms
====================================================================================================
 64KiB  (128*128 *  4) = 130.49ms
 128KiB (128*128 *  8) = 131.86ms
 256KiB (128*128 * 16) = 130.49ms
====================================================================================================
 256KiB (128*128 *  4) = 523.45ms
 512KiB (128*128 *  8) = 517.18ms
 1MiB   (128*128 * 16) = 517.35ms
 Done.