[Perf] Linux/x64: 2 Improvements on 9/9/2026 12:24:10 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [0d5b6c0b6ecc39cd272912814c71e898929cbec6](https://github.com/dotnet/runtime/commit/0d5b6c0b6ecc39cd272912814c71e898929cbec6)
Compare | [bd7f7404b0b4ad43847b20e0cb9f16a9e13cd4f8](https://github.com/dotnet/runtime/commit/bd7f7404b0b4ad43847b20e0cb9f16a9e13cd4f8)
Diff | [Diff](https://github.com/dotnet/runtime/compare/0d5b6c0b6ecc39cd272912814c71e898929cbec6...bd7f7404b0b4ad43847b20e0cb9f16a9e13cd4f8)
Configs | CompilationMode:wasm, RunKind:micro

### Improvements in System.IO.Tests.Perf_FileStream

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

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

| 1.49 ms | 1.25 ms | 0.84 | 0.07 | False | | |
|

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

| 664.92 ms | 571.56 ms | 0.86 | 0.09 | False | | |

![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.Write_NoBuffering(fileSize: 1048576, userBufferSize: 16384, options: Asynchronous)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.Perf_FileStream.Write(fileSize: 104857600, userBufferSize: 4096, options: None)

#### 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 two benchmark entries in performance/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.FileStream.cs, at lines 225-233, and read the benchmarking workflow linked in the issue. Run benchmarks_ci.py with the provided filter, then compare the baseline and test reports to investigate the FileStream improvements under wasm on Ubuntu. Done requires identifying and addressing the cause of the measured change, though the issue does not specify an expected fix.

Written by the indexing model from the issue text.