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IterateData has setup overhead of 480 μs (10%). There remained strange setup overhead after extracting the data into setUpFunction, because of of-by-one error in the main loop. It should be either: `for _ 1…10*N` or: `for _ 0..<10*N`. It’s error to use 0…m*N, because this will result in `m*N + 1` iterations that will be divided by N in the reported measurement. The extra iteration then manifests as a mysterious setup overhead!
39 lines
1.0 KiB
Swift
39 lines
1.0 KiB
Swift
//===--- IterateData.swift ------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import TestsUtils
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import Foundation
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public let IterateData = BenchmarkInfo(
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name: "IterateData",
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runFunction: run_IterateData,
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tags: [.validation, .api, .Data],
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setUpFunction: { blackHole(data) })
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let data: Data = {
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var data = Data(count: 16 * 1024)
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let n = data.count
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data.withUnsafeMutableBytes { (ptr: UnsafeMutablePointer<UInt8>) -> () in
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for i in 0..<n {
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ptr[i] = UInt8(i % 23)
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}
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}
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return data
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}()
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@inline(never)
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public func run_IterateData(_ N: Int) {
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for _ in 1...10*N {
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_ = data.reduce(0, &+)
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}
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}
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