[Perf -14%] System.Tests.Perf_UInt32.TryParseHex

[DrewScoggins]

Run Information

Architecture	x64
OS	ubuntu 18.04
Changes	diff

Regressions in System.Tests.Perf_UInt32

Benchmark	Baseline	Test	Test/Base	Modality	Baseline Outlier
TryParseHex	15.14 ns	17.49 ns	1.16	Bimodal	False

Historical Data in Reporting System

Repro

git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f netcoreapp5.0 --filter 'System.Tests.Perf_UInt32*';

Details

Histogram

System.Tests.Perf_UInt32.TryParseHex(value: "FFFFFFFF")

[14.487 ; 14.918) | @@@
[14.918 ; 15.494) | @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
[15.494 ; 15.920) | @@@
[15.920 ; 16.496) | 
[16.496 ; 16.855) | 
[16.855 ; 17.250) | @@@@@@@@
[17.250 ; 17.826) | @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
[17.826 ; 18.411) | @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
[18.411 ; 18.967) | @@@@@@
[18.967 ; 19.543) | 
[19.543 ; 20.119) | 
[20.119 ; 20.695) | 
[20.695 ; 21.323) | 
[21.323 ; 21.899) | @

Docs

Profiling workflow for dotnet/runtime repository
Benchmarking workflow for dotnet/runtime repository

[Dotnet-GitSync-Bot]

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[danmoseley]

@DrewScoggins please include a diff link showing changes closely bracketing regression. This one does not work. I believe this is important for all regression issues.

[DrewScoggins]

#39122 (comment)

This should help you track down the diff.

[stephentoub]

I can't repro this locally on Ubuntu 18.04. All inputs to this test show improvement for me:

dotnet run -c Release -f netcoreapp3.1 --runtimes netcoreapp3.1 netcoreapp5.0 --join --filter *System.Tests.Perf_UInt32.TryParseHex*

Method	Job	Runtime	Toolchain	value	Mean	Error	StdDev	Median	Min	Max	Ratio
TryParseHex	Job-WVEAVH	.NET Core 3.1	netcoreapp3.1	0	10.219 ns	0.0542 ns	0.0480 ns	10.204 ns	10.125 ns	10.317 ns	1.00
TryParseHex	Job-ZMIWWJ	.NET Core 5.0	netcoreapp5.0	0	8.613 ns	0.0618 ns	0.0578 ns	8.583 ns	8.554 ns	8.732 ns	0.84
TryParseHex	Job-WVEAVH	.NET Core 3.1	netcoreapp3.1	3039	14.377 ns	0.1322 ns	0.1104 ns	14.356 ns	14.227 ns	14.556 ns	1.00
TryParseHex	Job-ZMIWWJ	.NET Core 5.0	netcoreapp5.0	3039	13.265 ns	0.0622 ns	0.0552 ns	13.271 ns	13.148 ns	13.355 ns	0.92
TryParseHex	Job-WVEAVH	.NET Core 3.1	netcoreapp3.1	FFFFFFFF	19.740 ns	0.1613 ns	0.1347 ns	19.765 ns	19.464 ns	19.950 ns	1.00
TryParseHex	Job-ZMIWWJ	.NET Core 5.0	netcoreapp5.0	FFFFFFFF	18.601 ns	0.1318 ns	0.1233 ns	18.604 ns	18.430 ns	18.842 ns	0.94

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[danmoseley]

I looked at the diffs for each transition back and forth in Dec and Jan and nothing stands out as relevant. Since there's not a local repro, I don't think this issue is useful.