[Perf] Linux/arm64: 1 Regression on 6/28/2026 11:38:01 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [d6d9a97587fbc88e5f934e0ec38e40b67dbe7c28](https://github.com/dotnet/runtime/commit/d6d9a97587fbc88e5f934e0ec38e40b67dbe7c28)
Compare | [664063fb61eba41e577746a03b0a3fbf8371dd17](https://github.com/dotnet/runtime/commit/664063fb61eba41e577746a03b0a3fbf8371dd17)
Diff | [Diff](https://github.com/dotnet/runtime/compare/d6d9a97587fbc88e5f934e0ec38e40b67dbe7c28...664063fb61eba41e577746a03b0a3fbf8371dd17)
Configs | CompilationMode:tiered, R2RType:r2r_interpreter, RunKind:micro

### Regressions in System.Collections.AddGivenSize<Int32>

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

• [ConcurrentDictionary - 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.Collections.AddGivenSize*'
```

### System.Collections.AddGivenSize<Int32>.ConcurrentDictionary(Size: 512)

#### 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 System.Collections.AddGivenSize.ConcurrentDictionary benchmark and its source at src/benchmarks/micro/libraries/System.Collections/Add/AddGivenSize.cs#L116-L124. Run the provided benchmarks_ci.py command, then compare the linked baseline and test reports for the Linux/arm64 configuration. Done means identifying and resolving the reported performance regression and confirming the benchmark no longer regresses.

Written by the indexing model from the issue text.