[Perf] Linux/arm64: 1 Improvement on 7/2/2026 11:21:29 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [901aeddd1c55f5fc5a1c1450f234dd954c430ea5](https://github.com/dotnet/runtime/commit/901aeddd1c55f5fc5a1c1450f234dd954c430ea5)
Compare | [e1979b72ccb5f916649f1d9949ef663254790c25](https://github.com/dotnet/runtime/commit/e1979b72ccb5f916649f1d9949ef663254790c25)
Diff | [Diff](https://github.com/dotnet/runtime/compare/901aeddd1c55f5fc5a1c1450f234dd954c430ea5...e1979b72ccb5f916649f1d9949ef663254790c25)
Configs | CompilationMode:tiered, R2RType:r2r_interpreter, RunKind:micro

### Improvements in System.Collections.CopyTo<String>

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

• [ReadOnlySpan - 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.CopyTo*'
```

### System.Collections.CopyTo<String>.ReadOnlySpan(Size: 2048)

#### 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 performance/src/benchmarks/micro/libraries/System.Collections/CopyTo.cs and the benchmarking workflow linked in the issue. Run the provided benchmarks_ci.py command for System.Collections.CopyTo, then compare the reported baseline and test results to determine whether the ARM64 improvement needs follow-up; the issue does not specify a code change or acceptance criteria.

Written by the indexing model from the issue text.