Guid Generation Performance Deteriorated in 2.1 vs 2.0 on OSX

[conradakunga]

Running some benchmarks on Guid Generation on OSX 10.13.4 High Sierra shows quite some performance degradation between .NET Core 2.0.6 and 2.1.0-preview2, as reported using benchmark.net

The code itself:

[Benchmark]
public Guid GenerateGuid()
{
    return Guid.NewGuid();
}

Below are the results on OSX

Method	Toolchain	Mean	Allocated
GenerateGuid	.NET Core 2.1	2,601.0 ns	0 B
GenerateGuid	.NET Core 2.0	279.0 ns	0 B

Below are the results for the same benchmark on Ubuntu 16.04

Method	Toolchain	Mean	Allocated
GenerateGuid	.NET Core 2.0	9.513 us	0 B
GenerateGuid	.NET Core 2.1	3.053 us	0 B

The variance between the OSX and Linux aside, what could lead to a 10x performance degradation?

[stephentoub]

cc: @janvorli

[ghost]

what could lead to a 10x performance degradation

dotnet/coreclr#16643

In 2.1, GUID is re-implemented in CoreCLR using a custom made CoCreateGuid function: https://github.com/janvorli/coreclr/blob/3b9f14d569182ac46a049965a630dfcd9e57d1dd/src/palrt/guid.cpp#L28-L48

In 2.0 is using libuuid.

[conradakunga]

If we ignore the slowdown frpm 2.0 to 2.1 for a moment, is that to say Guid generation on OSX regardless of generation technique (libuuid or custom function) is inherently slow? Let me re-post the benchmark numbers with the specs of the machines I run them on, using the same versions of .NET Core 2.0. and 2.1

BenchmarkDotNet=v0.10.14, OS=macOS High Sierra 10.13.4 (17E202) [Darwin 17.5.0]
Intel Core i7-3740QM CPU 2.70GHz (Ivy Bridge), 1 CPU, 8 logical and 4 physical cores
.NET Core SDK=2.1.300-preview2-008533
[Host] : .NET Core 2.0.6 (CoreCLR 4.6.0.0, CoreFX 4.6.26212.01), 64bit RyuJIT
Job-LGSHYZ : .NET Core 2.1.0-preview2-26406-04 (CoreCLR 4.6.26406.07, CoreFX 4.6.26406.04), 64bit RyuJIT
Job-EVVLKQ : .NET Core 2.0.6 (CoreCLR 4.6.0.0, CoreFX 4.6.26212.01), 64bit RyuJIT

Method	Toolchain	Mean	Allocated
GenerateGuid	.NET Core 2.1	2,601.0 ns	0 B
GenerateGuid	.NET Core 2.0	279.0 ns	0 B

BenchmarkDotNet=v0.10.14, OS=ubuntu 16.04
Intel Core i3-4005U CPU 1.70GHz (Haswell), 1 CPU, 4 logical and 2 physical cores
.NET Core SDK=2.1.300-preview2-008533
[Host] : .NET Core 2.0.6 (CoreCLR 4.6.0.0, CoreFX 4.6.26212.01), 64bit RyuJIT
Job-DMZZXU : .NET Core 2.0.6 (CoreCLR 4.6.0.0, CoreFX 4.6.26212.01), 64bit RyuJIT
Job-WHVDVG : .NET Core 2.1.0-preview2-26406-04 (CoreCLR 4.6.26406.07, CoreFX 4.6.26406.04), 64bit RyuJIT

Method	Toolchain	Mean	Allocated
GenerateGuid	.NET Core 2.0	9.274 us	0 B
GenerateGuid	.NET Core 2.1	3.043 us	0 B

Couple of things

1. On Core 2.1 Pefrormance has actually improved 3x on the Linux box
2. On Core 2.0 performance is ~ 30x slower on the Mac, and the Linux machine is much lower spec

[ghost]

is that to say Guid generation on OSX ... is inherently slow

I think no. That's why this issue was marked with label bug and added to the current milestone 2.1, which means it will most like be fixed before 2.1 release.
Would be interesting to find out what is the hotpath in macOS causing this regression using micro benchmark.

[stephentoub]

@janvorli is working on a fix.

[janvorli]

Fixed

[stephentoub]

Re-opening to track port to release/2.1.

[danmoseley]

Ported

[danmoseley]

Thanks @conradakunga perhaps you can try latest daily build tomorrow and confirm it's fixed?