[Perf] Linux/x64: 2 Regressions on 8/28/2026 11:31:31 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [100da3f94464f99616ee4a401670bec491ebc787](https://github.com/dotnet/runtime/commit/100da3f94464f99616ee4a401670bec491ebc787)
Compare | [aa036afce592ad80e938a35bd376222fb232cba9](https://github.com/dotnet/runtime/commit/aa036afce592ad80e938a35bd376222fb232cba9)
Diff | [Diff](https://github.com/dotnet/runtime/compare/100da3f94464f99616ee4a401670bec491ebc787...aa036afce592ad80e938a35bd376222fb232cba9)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in System.IO.Tests.Perf_File

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

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

| 1.71 ms | 1.86 ms | 1.09 | 0.11 | False | | |

![graph]()
[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.Tests.Perf_File*'
```

### System.IO.Tests.Perf_File.CopyToOverwrite(size: 1048576)

#### 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 | [100da3f94464f99616ee4a401670bec491ebc787](https://github.com/dotnet/runtime/commit/100da3f94464f99616ee4a401670bec491ebc787)
Compare | [aa036afce592ad80e938a35bd376222fb232cba9](https://github.com/dotnet/runtime/commit/aa036afce592ad80e938a35bd376222fb232cba9)
Diff | [Diff](https://github.com/dotnet/runtime/compare/100da3f94464f99616ee4a401670bec491ebc787...aa036afce592ad80e938a35bd376222fb232cba9)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in Microsoft.Extensions.DependencyInjection.ActivatorUtilitiesBenchmark

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

• [CreateInstance_5 - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 31.13 μs | 36.82 μs | 1.18 | 0.20 | False | | |

![graph]()
[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.DependencyInjection.ActivatorUtilitiesBenchmark*'
```

### Microsoft.Extensions.DependencyInjection.ActivatorUtilitiesBenchmark.CreateInstance_5

#### 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)

Start with the reported benchmark sources, src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs and src/benchmarks/micro/libraries/Microsoft.Extensions.DependencyInjection/ActivatorUtilitiesBenchmark.cs. Run the two provided benchmarks with benchmarks_ci.py, then compare the baseline and test commits and review their reports. Done means the regression cause is confirmed and the affected benchmarks no longer show the reported slowdown.

Written by the indexing model from the issue text.