[Perf] Linux/x64: 3 Regressions on 3/26/2026 3:05:03 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [a4bfa0d8a4fdc513c9a8d3dec57931c901e8ef2b](https://github.com/dotnet/runtime/commit/a4bfa0d8a4fdc513c9a8d3dec57931c901e8ef2b)
Compare | [487cc8c4a5776931d7d573444f2b6c08b65f1e27](https://github.com/dotnet/runtime/commit/487cc8c4a5776931d7d573444f2b6c08b65f1e27)
Diff | [Diff](https://github.com/dotnet/runtime/compare/a4bfa0d8a4fdc513c9a8d3dec57931c901e8ef2b...487cc8c4a5776931d7d573444f2b6c08b65f1e27)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Regressions in System.Tests.Perf_String

Benchmark | Baseline | Test | Test/Base | Test Quality | Edge Detector | Baseline IR | Compare IR | IR Ratio
-- | -- | -- | -- | -- | -- | -- | -- | --
|

• [Substring_Int - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 8.79 ns | 12.71 ns | 1.45 | 0.31 | False | | |

[Test Report]()

### 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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Tests.Perf_String*'
```

### System.Tests.Perf_String.Substring_Int(s: "dzsdzsDDZSDZSDZSddsz", i: 0)

#### 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)

---

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [a4bfa0d8a4fdc513c9a8d3dec57931c901e8ef2b](https://github.com/dotnet/runtime/commit/a4bfa0d8a4fdc513c9a8d3dec57931c901e8ef2b)
Compare | [487cc8c4a5776931d7d573444f2b6c08b65f1e27](https://github.com/dotnet/runtime/commit/487cc8c4a5776931d7d573444f2b6c08b65f1e27)
Diff | [Diff](https://github.com/dotnet/runtime/compare/a4bfa0d8a4fdc513c9a8d3dec57931c901e8ef2b...487cc8c4a5776931d7d573444f2b6c08b65f1e27)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Regressions in Microsoft.Extensions.Primitives.Performance.StringValuesBenchmark

Benchmark | Baseline | Test | Test/Base | Test Quality | Edge Detector | Baseline IR | Compare IR | IR Ratio
-- | -- | -- | -- | -- | -- | -- | -- | --
|

• [Count_Array - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 4.74 ns | 5.94 ns | 1.25 | 0.33 | False | | |

[Test Report]()

### 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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'Microsoft.Extensions.Primitives.Performance.StringValuesBenchmark*'
```

### Microsoft.Extensions.Primitives.Performance.StringValuesBenchmark.Count_Array

#### 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)

---

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [a4bfa0d8a4fdc513c9a8d3dec57931c901e8ef2b](https://github.com/dotnet/runtime/commit/a4bfa0d8a4fdc513c9a8d3dec57931c901e8ef2b)
Compare | [487cc8c4a5776931d7d573444f2b6c08b65f1e27](https://github.com/dotnet/runtime/commit/487cc8c4a5776931d7d573444f2b6c08b65f1e27)
Diff | [Diff](https://github.com/dotnet/runtime/compare/a4bfa0d8a4fdc513c9a8d3dec57931c901e8ef2b...487cc8c4a5776931d7d573444f2b6c08b65f1e27)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Regressions in System.IO.MemoryMappedFiles.Tests.Perf_MemoryMappedFile

Benchmark | Baseline | Test | Test/Base | Test Quality | Edge Detector | Baseline IR | Compare IR | IR Ratio
-- | -- | -- | -- | -- | -- | -- | -- | --
|

• [CreateNew - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 23.59 μs | 28.12 μs | 1.19 | 0.20 | False | | |

[Test Report]()

### 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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.IO.MemoryMappedFiles.Tests.Perf_MemoryMappedFile*'
```

### System.IO.MemoryMappedFiles.Tests.Perf_MemoryMappedFile.CreateNew(capacity: 100000)

#### 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)