[Perf] Linux/arm64: 1 Regression on 8/8/2026 7:59:35 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | ubuntu 22.04
Queue | AmpereUbuntu
Baseline | [4c86c57ac3a6569063da4cb0a7245aadbc276f00](https://github.com/dotnet/runtime/commit/4c86c57ac3a6569063da4cb0a7245aadbc276f00)
Compare | [9904b9343c89c898fea3a9dfa68a6aba7fa8f3c1](https://github.com/dotnet/runtime/commit/9904b9343c89c898fea3a9dfa68a6aba7fa8f3c1)
Diff | [Diff](https://github.com/dotnet/runtime/compare/4c86c57ac3a6569063da4cb0a7245aadbc276f00...9904b9343c89c898fea3a9dfa68a6aba7fa8f3c1)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.IO.Tests.Perf_FileInfo

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

• [ctor_str - 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_FileInfo*'
```

### System.IO.Tests.Perf_FileInfo.ctor_str

#### 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.FileInfo.cs and compare the listed baseline and compare commits. Run benchmarks_ci.py with the provided System.IO.Tests.Perf_FileInfo filter on the AmpereUbuntu ARM64 environment, then use the linked regression and profiling reports to identify the cause. Done means the regression is explained and an appropriate fix or follow-up is recorded.

Written by the indexing model from the issue text.