[Perf] Linux/arm64: 1 Improvement on 9/2/2026 9:00:27 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [696fda84063459254633ad07bf8ce1e6977c9ad5](https://github.com/dotnet/runtime/commit/696fda84063459254633ad07bf8ce1e6977c9ad5)
Compare | [1389900725bbe2c6fa69210a9a4c95f9ce42c5f0](https://github.com/dotnet/runtime/commit/1389900725bbe2c6fa69210a9a4c95f9ce42c5f0)
Diff | [Diff](https://github.com/dotnet/runtime/compare/696fda84063459254633ad07bf8ce1e6977c9ad5...1389900725bbe2c6fa69210a9a4c95f9ce42c5f0)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.IO.Tests.Perf_RandomAccess

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

• [WriteAsync - 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
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.IO.Tests.Perf_RandomAccess*'
```

### System.IO.Tests.Perf_RandomAccess.WriteAsync(fileSize: 1048576, bufferSize: 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 src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.RandomAccess.cs, especially the WriteAsync benchmark, and follow the benchmarking workflow linked in the issue. Run the provided benchmarks_ci.py command and compare the arm64 AzureLinux result with the recorded baseline. Done means the improvement is reproducible and its performance impact is understood or documented for triage.

Written by the indexing model from the issue text.