[Perf] Linux/arm64: 1 Regression on 7/14/2026 11:32:42 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [ac220bb785a8db28a9a46517a648ad14f1d6e2f4](https://github.com/dotnet/runtime/commit/ac220bb785a8db28a9a46517a648ad14f1d6e2f4)
Compare | [1f4ca7e70872521704e061548307019100d501cf](https://github.com/dotnet/runtime/commit/1f4ca7e70872521704e061548307019100d501cf)
Diff | [Diff](https://github.com/dotnet/runtime/compare/ac220bb785a8db28a9a46517a648ad14f1d6e2f4...1f4ca7e70872521704e061548307019100d501cf)
Configs | CompilationMode:tiered, R2RType:r2r_interpreter, RunKind:micro

### Regressions in System.Buffers.Tests.RentReturnArrayPoolTests<Object>

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

• [SingleSerial - 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.Buffers.Tests.RentReturnArrayPoolTests*'
```

### System.Buffers.Tests.RentReturnArrayPoolTests<Object>.SingleSerial(RentalSize: 4096, ManipulateArray: False, Async: True, UseSharedPool: True)

#### 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 linked benchmark source, System.Buffers/ArrayPoolTests.cs lines 48-60, and run the supplied benchmarks_ci.py command for the named filter. Compare the baseline and compare commits on Linux/arm64 using the reported tiered R2R interpreter configuration. Done means the 1.21x regression is explained and a validated change removes or accounts for it.

Written by the indexing model from the issue text.