[Perf] Windows/x64: 2 Regressions on 7/31/2026 4:48:31 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [ba8afceee83540ed1d867987483f74d4ad2cfae9](https://github.com/dotnet/runtime/commit/ba8afceee83540ed1d867987483f74d4ad2cfae9)
Compare | [d5c739f99fa75a37ea863b06dd8d31a51965c8be](https://github.com/dotnet/runtime/commit/d5c739f99fa75a37ea863b06dd8d31a51965c8be)
Diff | [Diff](https://github.com/dotnet/runtime/compare/ba8afceee83540ed1d867987483f74d4ad2cfae9...d5c739f99fa75a37ea863b06dd8d31a51965c8be)
Configs | CompilationMode:tiered, RunKind:micro


### Regressions in System.Collections.Tests.Perf_BitArray

Benchmark | Baseline | Test | Test/Base | Test Quality | Edge Detector | Baseline IR | Compare IR | IR Ratio
-- | -- | -- | -- | -- | -- | -- | -- | --
|<ul><li>[BitArraySetLengthGrow - Duration of single invocation](<https://pvscmdupload.z22.web.core.windows.net/reports/allTestHistory/refs/heads/main_x64_Windows%2010.0.22631/ViperWindows/System.Collections.Tests.Perf_BitArray.BitArraySetLengthGrow(Size%3a%204).html>)</li><li>📝 - [Benchmark Source](<https://github.com/dotnet/performance/blob/main/src/benchmarks/micro/libraries/System.Collections/Perf.BitArray.cs#L120-#L127>)</li><li>[ADX - Test Multi Config Graph](<https://dataexplorer.azure.com/clusters/dotnetperf.westus/databases/PerformanceData?query=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>)</li></ul> | 21.52 ns | 26.69 ns | 1.24 | 0.21 | False | | |
|<ul><li>[BitArrayBoolArrayCtor - Duration of single invocation](<https://pvscmdupload.z22.web.core.windows.net/reports/allTestHistory/refs/heads/main_x64_Windows%2010.0.22631/ViperWindows/System.Collections.Tests.Perf_BitArray.BitArrayBoolArrayCtor(Size%3a%20512).html>)</li><li>📝 - [Benchmark Source](<https://github.com/dotnet/performance/blob/main/src/benchmarks/micro/libraries/System.Collections/Perf.BitArray.cs#L43-#L44>)</li><li>[ADX - Test Multi Config Graph](<https://dataexplorer.azure.com/clusters/dotnetperf.westus/databases/PerformanceData?query=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>)</li></ul> | 16.70 ns | 20.32 ns | 1.22 | 0.28 | False | | |

![graph](<https://pvscmdupload.z22.web.core.windows.net/autofilereport/autofilereports/08_04_2026/refs/heads/main_x64_Windows%2010.0.22631/ViperWindows_Regression/System.Collections.Tests.Perf_BitArray_001.png>)
![graph](<https://pvscmdupload.z22.web.core.windows.net/autofilereport/autofilereports/08_04_2026/refs/heads/main_x64_Windows%2010.0.22631/ViperWindows_Regression/System.Collections.Tests.Perf_BitArray_002.png>)
[Test Report](<https://pvscmdupload.z22.web.core.windows.net/autofilereport/autofilereports/08_04_2026/refs/heads/main_x64_Windows%2010.0.22631/ViperWindows_Regression/System.Collections.Tests.Perf_BitArray.html>)

### Repro
General Docs link: https://github.com/dotnet/performance/blob/main/docs/benchmarking-workflow-dotnet-runtime.md

```cmd
git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Collections.Tests.Perf_BitArray*'
```

<details>

### System.Collections.Tests.Perf_BitArray.BitArraySetLengthGrow(Size: 4)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Collections.Tests.Perf_BitArray.BitArrayBoolArrayCtor(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms



### Docs

[Profiling workflow for dotnet/runtime repository](https://github.com/dotnet/performance/blob/master/docs/profiling-workflow-dotnet-runtime.md)
[Benchmarking workflow for dotnet/runtime repository](https://github.com/dotnet/performance/blob/master/docs/benchmarking-workflow-dotnet-runtime.md)

</details>

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Uh oh!

[Perf] Windows/x64: 2 Regressions on 7/31/2026 4:48:31 PM +00:00 #131815

Run Information

Regressions in System.Collections.Tests.Perf_BitArray

Repro

System.Collections.Tests.Perf_BitArray.BitArraySetLengthGrow(Size: 4)

ETL Files

Histogram

JIT Disasms

System.Collections.Tests.Perf_BitArray.BitArrayBoolArrayCtor(Size: 512)

ETL Files

Histogram

JIT Disasms

Docs

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Name	Value
Architecture	x64
OS	Windows 10.0.22631
Queue	ViperWindows
Baseline	ba8afceee83540ed1d867987483f74d4ad2cfae9
Compare	d5c739f99fa75a37ea863b06dd8d31a51965c8be
Diff	Diff
Configs	CompilationMode:tiered, RunKind:micro

Benchmark	Baseline	Test	Test/Base	Test Quality	Edge Detector	Baseline IR	Compare IR	IR Ratio
BitArraySetLengthGrow - Duration of single invocation 📝 - Benchmark Source ADX - Test Multi Config Graph	21.52 ns	26.69 ns	1.24	0.21	False
BitArrayBoolArrayCtor - Duration of single invocation 📝 - Benchmark Source ADX - Test Multi Config Graph	16.70 ns	20.32 ns	1.22	0.28	False

Uh oh!

[Perf] Windows/x64: 2 Regressions on 7/31/2026 4:48:31 PM +00:00 #131815

Description

Run Information

Regressions in System.Collections.Tests.Perf_BitArray

Repro

System.Collections.Tests.Perf_BitArray.BitArraySetLengthGrow(Size: 4)

ETL Files

Histogram

JIT Disasms

System.Collections.Tests.Perf_BitArray.BitArrayBoolArrayCtor(Size: 512)

ETL Files

Histogram

JIT Disasms

Docs

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions