[Perf] Linux/arm64: 4 Regressions on 8/11/2026 9:14:21 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [643b8962835e549e8f6c88fd8b19f6f79685fba0](https://github.com/dotnet/runtime/commit/643b8962835e549e8f6c88fd8b19f6f79685fba0)
Compare | [633ab1a41439ad2405ba2eb241295ba1842fcf5a](https://github.com/dotnet/runtime/commit/633ab1a41439ad2405ba2eb241295ba1842fcf5a)
Diff | [Diff](https://github.com/dotnet/runtime/compare/643b8962835e549e8f6c88fd8b19f6f79685fba0...633ab1a41439ad2405ba2eb241295ba1842fcf5a)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Linq.Tests.Perf_Enumerable

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

• [Select - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 438.41 ns | 504.23 ns | 1.15 | 0.11 | False | | |
|

• [Select - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 439.32 ns | 504.42 ns | 1.15 | 0.20 | False | | |
|

• [Select - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 439.01 ns | 503.81 ns | 1.15 | 0.21 | False | | |
|

• [Concat_Once - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 792.66 ns | 881.50 ns | 1.11 | 0.16 | False | | |

![graph]()
![graph]()
![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.Linq.Tests.Perf_Enumerable*'
```

### System.Linq.Tests.Perf_Enumerable.Select(input: IEnumerable)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Linq.Tests.Perf_Enumerable.Select(input: List)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Linq.Tests.Perf_Enumerable.Select(input: IList)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Linq.Tests.Perf_Enumerable.Concat_Once(input: IEnumerable)

#### 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)