[Perf] Linux/arm64: 1 Regression on 7/8/2026 3:24:30 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [f475c19ddfd8b94cd311712cb799c4be14bd6d31](https://github.com/dotnet/runtime/commit/f475c19ddfd8b94cd311712cb799c4be14bd6d31)
Compare | [f9a6e2ef41c17130866d7036c5f0cde47e8854af](https://github.com/dotnet/runtime/commit/f9a6e2ef41c17130866d7036c5f0cde47e8854af)
Diff | [Diff](https://github.com/dotnet/runtime/compare/f475c19ddfd8b94cd311712cb799c4be14bd6d31...f9a6e2ef41c17130866d7036c5f0cde47e8854af)
Configs | CompilationMode:tiered, R2RType:r2r_interpreter, RunKind:micro

### Regressions in System.Runtime.Intrinsics.Tests.Perf_Vector128Of<Int32>

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

• [SumBenchmark - 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.Runtime.Intrinsics.Tests.Perf_Vector128Of*'
```

### System.Runtime.Intrinsics.Tests.Perf_Vector128Of<Int32>.SumBenchmark

#### 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.Runtime.Intrinsics/Perf_Vector128OfT.cs#L166-L167 and the linked baseline/compare commits. Run the provided benchmarks_ci.py command using the benchmarking workflow documentation, then inspect the benchmark and test reports to identify the cause of the 1.85x arm64 regression. Done means the regression is explained and the benchmark result is restored or otherwise accounted for.

Written by the indexing model from the issue text.