[Perf] Linux/x64: 2 Regressions on 8/28/2026 11:31:31 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [100da3f94464f99616ee4a401670bec491ebc787](https://github.com/dotnet/runtime/commit/100da3f94464f99616ee4a401670bec491ebc787)
Compare | [aa036afce592ad80e938a35bd376222fb232cba9](https://github.com/dotnet/runtime/commit/aa036afce592ad80e938a35bd376222fb232cba9)
Diff | [Diff](https://github.com/dotnet/runtime/compare/100da3f94464f99616ee4a401670bec491ebc787...aa036afce592ad80e938a35bd376222fb232cba9)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Regressions in System.Text.Json.Tests.Utf8JsonReaderCommentsTests

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

• [Utf8JsonReaderCommentParsing - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 114.91 ns | 144.27 ns | 1.26 | 0.15 | False | | |
|

• [Utf8JsonReaderCommentParsing - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 169.72 ns | 193.03 ns | 1.14 | 0.13 | False | | |

![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
python3 .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Text.Json.Tests.Utf8JsonReaderCommentsTests*'
```

### System.Text.Json.Tests.Utf8JsonReaderCommentsTests.Utf8JsonReaderCommentParsing(CommentHandling: Skip, SegmentSize: 0, TestCase: ShortSingleLine)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.Json.Tests.Utf8JsonReaderCommentsTests.Utf8JsonReaderCommentParsing(CommentHandling: Skip, SegmentSize: 100, TestCase: ShortMultiLine)

#### 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 baseline and compare commits and the linked benchmark source, dotnet/performance/src/benchmarks/micro/libraries/System.Text.Json/Utf8JsonReader/Utf8JsonReader.Comments.Tests.cs#L51-L62. Run benchmarks_ci.py with the reported filter, then use the test report and profiling workflow to identify the cause of the two Linux/x64 AOT WebAssembly regressions. Done means the affected benchmarks no longer regress against the baseline.

Written by the indexing model from the issue text.