measureRunTime use DispatchTime #2545
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Motivation: Using `Date()` in benchmarks leaves us open to the possibility that a clock update could occur between the start and end times affecting the measured interval. Modifications: Switch `measureRunTime` and related functions to use `DispatchTime` uptime in nanoseconds to calculate intervals Result: Tests should no longer be susceptible to clock updates.
glbrntt
reviewed
Oct 10, 2023
| @@ -37,7 +37,7 @@ public func measureRunTime(_ body: () throws -> Int) rethrows -> TimeInterval { | |||
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| public func measureRunTimeAndPrint(desc: String, body: () throws -> Int) rethrows -> Void { | |||
| print("measuring: \(desc)") | |||
| print("\(try measureRunTime(body))s") | |||
| print("\(try measureRunTime(body)/1_000_000)s") | |||
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We should probably do floating point arithmetic here
| @@ -119,7 +119,8 @@ func runSystemCallWrapperPerformanceTest(testAssertFunction: (@autoclosure () -> | |||
| precondition(isDebugMode) | |||
| print("WARNING: Syscall wrapper test: Over 100% overhead allowed. Running in debug assert configuration which allows \(allowedOverheadPercent)% overhead :(. Consider running in Release mode.") | |||
| } | |||
| testAssertFunction(directCallTime * (1.0 + Double(allowedOverheadPercent)/100) > withSystemCallWrappersTime, | |||
| let upper = Double(directCallTime) * (1.0 + Double(allowedOverheadPercent)/100) | |||
| testAssertFunction( upper > Double(withSystemCallWrappersTime), | |||
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Suggested change
| testAssertFunction( upper > Double(withSystemCallWrappersTime), | |
| testAssertFunction(upper > Double(withSystemCallWrappersTime), |
Lukasa
reviewed
Oct 10, 2023
| public func measureRunTime(_ body: () throws -> Int) rethrows -> TimeInterval { | ||
| func measureOne(_ body: () throws -> Int) rethrows -> TimeInterval { | ||
| let start = Date() | ||
| public func measureRunTime(_ body: () throws -> Int) rethrows -> UInt64 { |
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It will probably make your life easier to keep the function signature the same, and just compute the TimeInterval internal to measureOne.
glbrntt
approved these changes
Oct 11, 2023
FranzBusch
added
the
needs-no-version-bump
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Motivation:
Using
Date()in benchmarks leaves us open to the possibility that a clock update could occur between the start and end times affecting the measured interval.Modifications:
Switch
measureRunTimeand related functions to useDispatchTimeuptime in nanoseconds to calculate intervalsResult:
Tests should no longer be susceptible to clock updates.