[Perf] Linux/arm64: 4 Regressions on 7/17/2026 12:15:56 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [b78a8f8b1d15898ba39eb4fd63e2578edcf16c37](https://github.com/dotnet/runtime/commit/b78a8f8b1d15898ba39eb4fd63e2578edcf16c37)
Compare | [09f41d9272e6dcff30bfa15653e124d013167e05](https://github.com/dotnet/runtime/commit/09f41d9272e6dcff30bfa15653e124d013167e05)
Diff | [Diff](https://github.com/dotnet/runtime/compare/b78a8f8b1d15898ba39eb4fd63e2578edcf16c37...09f41d9272e6dcff30bfa15653e124d013167e05)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Runtime.Intrinsics.Tests.Perf_Vector128Of<Byte>

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

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

| 43.34 ns | 60.31 ns | 1.39 | 0.24 | False | | |

![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.Runtime.Intrinsics.Tests.Perf_Vector128Of*'
```

### System.Runtime.Intrinsics.Tests.Perf_Vector128Of<Byte>.SquareRootBenchmark

#### 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)

---

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [b78a8f8b1d15898ba39eb4fd63e2578edcf16c37](https://github.com/dotnet/runtime/commit/b78a8f8b1d15898ba39eb4fd63e2578edcf16c37)
Compare | [09f41d9272e6dcff30bfa15653e124d013167e05](https://github.com/dotnet/runtime/commit/09f41d9272e6dcff30bfa15653e124d013167e05)
Diff | [Diff](https://github.com/dotnet/runtime/compare/b78a8f8b1d15898ba39eb4fd63e2578edcf16c37...09f41d9272e6dcff30bfa15653e124d013167e05)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Runtime.Intrinsics.Tests.Perf_Vector128Of<UInt16>

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

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

| 36.20 ns | 45.00 ns | 1.24 | 0.53 | False | | |

![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.Runtime.Intrinsics.Tests.Perf_Vector128Of*'
```

### System.Runtime.Intrinsics.Tests.Perf_Vector128Of<UInt16>.SquareRootBenchmark

#### 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)

---

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [b78a8f8b1d15898ba39eb4fd63e2578edcf16c37](https://github.com/dotnet/runtime/commit/b78a8f8b1d15898ba39eb4fd63e2578edcf16c37)
Compare | [09f41d9272e6dcff30bfa15653e124d013167e05](https://github.com/dotnet/runtime/commit/09f41d9272e6dcff30bfa15653e124d013167e05)
Diff | [Diff](https://github.com/dotnet/runtime/compare/b78a8f8b1d15898ba39eb4fd63e2578edcf16c37...09f41d9272e6dcff30bfa15653e124d013167e05)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Numerics.Tests.Perf_VectorOf<Byte>

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

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

| 28.48 ns | 34.56 ns | 1.21 | 0.55 | False | | |

![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.Numerics.Tests.Perf_VectorOf*'
```

### System.Numerics.Tests.Perf_VectorOf<Byte>.SquareRootBenchmark

#### 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)

---

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [b78a8f8b1d15898ba39eb4fd63e2578edcf16c37](https://github.com/dotnet/runtime/commit/b78a8f8b1d15898ba39eb4fd63e2578edcf16c37)
Compare | [09f41d9272e6dcff30bfa15653e124d013167e05](https://github.com/dotnet/runtime/commit/09f41d9272e6dcff30bfa15653e124d013167e05)
Diff | [Diff](https://github.com/dotnet/runtime/compare/b78a8f8b1d15898ba39eb4fd63e2578edcf16c37...09f41d9272e6dcff30bfa15653e124d013167e05)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Numerics.Tests.Perf_VectorOf<Int16>

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

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

| 20.62 ns | 28.80 ns | 1.40 | 0.20 | False | | |

![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.Numerics.Tests.Perf_VectorOf*'
```

### System.Numerics.Tests.Perf_VectorOf<Int16>.SquareRootBenchmark

#### 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 regression reports and the benchmark sources at src/benchmarks/micro/libraries/System.Runtime.Intrinsics/Perf_Vector128OfT.cs and src/benchmarks/micro/libraries/System.Numerics.Vectors/Perf_VectorOfT.cs. Reproduce the listed filters with scripts/benchmarks_ci.py, then compare the baseline and test commits and inspect the profiling workflow; done means identifying the cause of the ARM64 regressions and verifying the affected benchmarks no longer regress.

Written by the indexing model from the issue text.