[Perf] Linux/x64: 1 Regression on 8/5/2026 1:23:13 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [ac85c6849c56dcb47e036b2a729c1e99dc413bab](https://github.com/dotnet/runtime/commit/ac85c6849c56dcb47e036b2a729c1e99dc413bab)
Compare | [c8f97975ab0d8ff84aebf176829e17f7c7052f03](https://github.com/dotnet/runtime/commit/c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Diff | [Diff](https://github.com/dotnet/runtime/compare/ac85c6849c56dcb47e036b2a729c1e99dc413bab...c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Configs | CompilationMode:wasm, RunKind:micro

### Regressions in System.IO.Tests.Perf_FileStream

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

• [Read_NoBuffering - 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_FileStream*'
```

### System.IO.Tests.Perf_FileStream.Read_NoBuffering(fileSize: 104857600, userBufferSize: 16384, options: Asynchronous)

#### 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 in performance/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.FileStream.cs at lines 204-207 and compare the listed baseline and regression commits. Follow the benchmarking workflow and run the provided benchmarks_ci.py command for System.IO.Tests.Perf_FileStream; done means the regression is explained and the benchmark no longer shows the reported slowdown.

Written by the indexing model from the issue text.