[Perf] Linux/arm64: 5 Improvements on 8/10/2026 5:38:55 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | ubuntu 22.04
Queue | AmpereUbuntu
Baseline | [98037590c8dd74cf65d3cde986af6d03ba0da2f3](https://github.com/dotnet/runtime/commit/98037590c8dd74cf65d3cde986af6d03ba0da2f3)
Compare | [6597edb0936de18005623b1a17adf29880df60e6](https://github.com/dotnet/runtime/commit/6597edb0936de18005623b1a17adf29880df60e6)
Diff | [Diff](https://github.com/dotnet/runtime/compare/98037590c8dd74cf65d3cde986af6d03ba0da2f3...6597edb0936de18005623b1a17adf29880df60e6)
Configs | CompilationMode:tiered, RunKind:micro

### Improvements in System.Formats.Tar.Tests.Perf_TarWriter

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

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

| 534.48 ns | 359.14 ns | 0.67 | 0.15 | False | | |
|

• [V7TarEntry_WriteEntry - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 526.57 ns | 369.85 ns | 0.70 | 0.12 | False | | |
|

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

| 542.56 ns | 384.02 ns | 0.71 | 0.12 | False | | |
|

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

| 2.73 μs | 2.04 μs | 0.75 | 0.16 | False | | |
|

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

| 2.78 μs | 2.33 μs | 0.84 | 0.14 | False | | |

![graph]()
![graph]()
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[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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Formats.Tar.Tests.Perf_TarWriter*'
```

### System.Formats.Tar.Tests.Perf_TarWriter.UstarTarEntry_WriteEntry

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Formats.Tar.Tests.Perf_TarWriter.V7TarEntry_WriteEntry

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Formats.Tar.Tests.Perf_TarWriter.GnuTarEntry_WriteEntry

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Formats.Tar.Tests.Perf_TarWriter.PaxTarEntry_WriteEntry

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Formats.Tar.Tests.Perf_TarWriter.PaxTarEntry_WriteEntry_Async

#### 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 at performance/src/benchmarks/micro/libraries/System.Formats.Tar/Perf.Tar.cs lines 45-99 and review the linked performance report. Run the provided benchmarks_ci.py command to reproduce the arm64 results. The report identifies improvements but does not specify a requested code change or a clear completion condition.

Written by the indexing model from the issue text.