[Perf] Linux/x64: 1 Regression on 5/5/2026 8:56:26 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [004c358f4376950ead5ef31b95bf4f91a725b42a](https://github.com/dotnet/runtime/commit/004c358f4376950ead5ef31b95bf4f91a725b42a)
Compare | [2e33a3e335d509dda962bf1ca463d6c970b7393b](https://github.com/dotnet/runtime/commit/2e33a3e335d509dda962bf1ca463d6c970b7393b)
Diff | [Diff](https://github.com/dotnet/runtime/compare/004c358f4376950ead5ef31b95bf4f91a725b42a...2e33a3e335d509dda962bf1ca463d6c970b7393b)
Configs | CompilationMode:wasm, RunKind:micro

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

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

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

![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.ReadAllBytes(size: 104857600)

#### 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 benchmark source at src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs#L124-L131 and compare the listed baseline and compare commits. Run the benchmarks_ci.py command for System.IO.Tests.Perf_File, then use the linked test and profiling reports to identify the cause of the ReadAllBytes regression. Done means the regression is explained and the benchmark returns to baseline performance.

Written by the indexing model from the issue text.