[Perf] Linux/x64: 5 Regressions on 4/12/2026 2:20:28 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [e583c98763e224e5d6587a9d8fc732a33b1d808b](https://github.com/dotnet/runtime/commit/e583c98763e224e5d6587a9d8fc732a33b1d808b)
Compare | [6df558c6c4b6b13d3f40c21ac7d61cf7bc13b96e](https://github.com/dotnet/runtime/commit/6df558c6c4b6b13d3f40c21ac7d61cf7bc13b96e)
Diff | [Diff](https://github.com/dotnet/runtime/compare/e583c98763e224e5d6587a9d8fc732a33b1d808b...6df558c6c4b6b13d3f40c21ac7d61cf7bc13b96e)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Text.Json.Tests.Perf_Reader

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

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

| 2.15 μs | 2.45 μs | 1.14 | 0.03 | False | | |
|

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

| 1.62 μs | 1.82 μs | 1.12 | 0.09 | False | | |
|

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

| 3.70 μs | 4.04 μs | 1.09 | 0.07 | False | | |
|

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

| 63.34 ns | 67.64 ns | 1.07 | 0.15 | False | | |

[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.Text.Json.Tests.Perf_Reader*'
```

### System.Text.Json.Tests.Perf_Reader.ReadSingleSpanSequenceEmptyLoop(IsDataCompact: True, TestCase: Json4KB)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.Json.Tests.Perf_Reader.ReadSingleSpanSequenceEmptyLoop(IsDataCompact: True, TestCase: DeepTree)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.Json.Tests.Perf_Reader.ReadSingleSpanSequenceEmptyLoop(IsDataCompact: True, TestCase: BroadTree)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.Json.Tests.Perf_Reader.ReadSingleSpanSequenceEmptyLoop(IsDataCompact: True, TestCase: HelloWorld)

#### 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 | [e583c98763e224e5d6587a9d8fc732a33b1d808b](https://github.com/dotnet/runtime/commit/e583c98763e224e5d6587a9d8fc732a33b1d808b)
Compare | [6df558c6c4b6b13d3f40c21ac7d61cf7bc13b96e](https://github.com/dotnet/runtime/commit/6df558c6c4b6b13d3f40c21ac7d61cf7bc13b96e)
Diff | [Diff](https://github.com/dotnet/runtime/compare/e583c98763e224e5d6587a9d8fc732a33b1d808b...6df558c6c4b6b13d3f40c21ac7d61cf7bc13b96e)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.IO.Tests.Perf_Path

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

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

| 18.18 ns | 21.12 ns | 1.16 | 0.19 | False | | |

[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.IO.Tests.Perf_Path*'
```

### System.IO.Tests.Perf_Path.GetFileNameWithoutExtension

#### 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)