[Perf] Linux/x64: 2 Regressions on 9/3/2026 9:59:06 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [334cc5c43dfb4b6acab5052c15ee8b1631d069bc](https://github.com/dotnet/runtime/commit/334cc5c43dfb4b6acab5052c15ee8b1631d069bc)
Compare | [134de00ac5934568c582a35322ae16a228db430d](https://github.com/dotnet/runtime/commit/134de00ac5934568c582a35322ae16a228db430d)
Diff | [Diff](https://github.com/dotnet/runtime/compare/334cc5c43dfb4b6acab5052c15ee8b1631d069bc...134de00ac5934568c582a35322ae16a228db430d)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in PerfLabTests.LowLevelPerf

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

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

| 135.63 μs | 189.84 μs | 1.40 | 0.49 | 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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'PerfLabTests.LowLevelPerf*'
```

### PerfLabTests.LowLevelPerf.GenericGenericMethod

#### 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 | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [334cc5c43dfb4b6acab5052c15ee8b1631d069bc](https://github.com/dotnet/runtime/commit/334cc5c43dfb4b6acab5052c15ee8b1631d069bc)
Compare | [134de00ac5934568c582a35322ae16a228db430d](https://github.com/dotnet/runtime/commit/134de00ac5934568c582a35322ae16a228db430d)
Diff | [Diff](https://github.com/dotnet/runtime/compare/334cc5c43dfb4b6acab5052c15ee8b1631d069bc...134de00ac5934568c582a35322ae16a228db430d)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Numerics.Tests.Perf_VectorConvert

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

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

| 550.82 ns | 590.85 ns | 1.07 | 0.02 | 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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Numerics.Tests.Perf_VectorConvert*'
```

### System.Numerics.Tests.Perf_VectorConvert.Narrow_ulong

#### 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 sources in src/benchmarks/micro/runtime/perflab/LowLevelPerf.cs and src/benchmarks/micro/libraries/System.Numerics.Vectors/Perf_VectorConvert.cs, then review the linked baseline-to-compare diff. Run the two benchmarks with scripts/benchmarks_ci.py and the filters shown in the issue. Done means confirming the regressions and identifying the responsible change for triage.

Written by the indexing model from the issue text.