[Perf] Linux/arm64: 1 Improvement on 8/28/2026 12:45:54 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [3174387aedaebdb35da41426e61ecc1b8d60bc47](https://github.com/dotnet/runtime/commit/3174387aedaebdb35da41426e61ecc1b8d60bc47)
Compare | [398b6c5d572103decd5cfec64121384bcffc01bc](https://github.com/dotnet/runtime/commit/398b6c5d572103decd5cfec64121384bcffc01bc)
Diff | [Diff](https://github.com/dotnet/runtime/compare/3174387aedaebdb35da41426e61ecc1b8d60bc47...398b6c5d572103decd5cfec64121384bcffc01bc)
Configs | CompilationMode:tiered, R2RType:r2r_interpreter, RunKind:micro

### Improvements in PerfLabTests.CastingPerf2.CastingPerf

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

• [FooObjCastIfIsa - 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 'PerfLabTests.CastingPerf2.CastingPerf*'
```

### PerfLabTests.CastingPerf2.CastingPerf.FooObjCastIfIsa

#### 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 src/benchmarks/micro/runtime/perflab/CastingPerf2.cs, especially lines 230-236, and read the benchmarking workflow linked in the issue. Run the provided benchmarks_ci.py command for CastingPerf2.CastingPerf and compare the reported ARM64 AzureLinux result with the linked history. Done means the improvement is understood and any resulting change is validated by the benchmark.

Written by the indexing model from the issue text.