[Perf] Linux/x64: 5 Regressions on 9/6/2026 6:55:28 PM +00:00

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#79,114 opened on Sep 8, 2026 1 comment 0 reactions 0 assignees View on GitHub

aot-true arch-wasm arch-x64 branch-refs/heads/main compilationmode-wasm kind-micro os-linux perf-regression runkind-micro untriaged wasm-aot

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Forks: 8
PR merge metrics: PR metrics pending

Description

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [5b11923ecac20a8367b4ca60a9b9739479319e9a](https://github.com/dotnet/runtime/commit/5b11923ecac20a8367b4ca60a9b9739479319e9a)
Compare | [570fcdab16c5b674bb59007f4faa705671d69cc2](https://github.com/dotnet/runtime/commit/570fcdab16c5b674bb59007f4faa705671d69cc2)
Diff | [Diff](https://github.com/dotnet/runtime/compare/5b11923ecac20a8367b4ca60a9b9739479319e9a...570fcdab16c5b674bb59007f4faa705671d69cc2)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Regressions in System.Numerics.Tests.Perf_BigInteger

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

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

| 25.38 ns | 45.38 ns | 1.79 | 0.24 | False | | |
|

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

| 30.07 ns | 33.37 ns | 1.11 | 0.11 | 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.Numerics.Tests.Perf_BigInteger*'
```

### System.Numerics.Tests.Perf_BigInteger.Remainder(arguments: 16,8 bits)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Numerics.Tests.Perf_BigInteger.GreatestCommonDivisor(arguments: 16,16 bits)

#### 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

### Regressions in System.IO.Tests.Perf_FileStream

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

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

| 39.66 μs | 48.63 μs | 1.23 | 0.12 | 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.IO.Tests.Perf_FileStream*'
```

### System.IO.Tests.Perf_FileStream.Read_NoBuffering(fileSize: 1048576, userBufferSize: 16384, options: Asynchronous)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Collections.CtorGivenSize<String>

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

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

| 834.76 ns | 944.18 ns | 1.13 | 0.29 | 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.Collections.CtorGivenSize*'
```

### System.Collections.CtorGivenSize<String>.Dictionary(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### 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]()

| 124.32 ns | 160.32 ns | 1.29 | 0.14 | 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.Text.Json.Tests.Utf8JsonReaderCommentsTests*'
```

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

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

Contributor guide

No contributing guide indexed for this repository

Research direction

Start with the baseline and compare commits, then reproduce the listed System.Numerics.Tests.Perf_BigInteger, System.IO.Tests.Perf_FileStream, and System.Collections.CtorGivenSize benchmarks using scripts/benchmarks_ci.py and the documented benchmarking workflow. Inspect the linked benchmark sources and performance reports; done means identifying the cause of the regressions and confirming the affected benchmarks no longer regress.

Written by the indexing model from the issue text.

Assessment

Tech stack: csharp, linux, python, ubuntu, wasm
Domain: performance, testing
Issue type: Bug
Difficulty: 4/5
Estimated time: 3-5 days
Activity status: Active
Clarity: Needs clarification
Newbie friendliness: 35/100

[Perf] Linux/x64: 5 Regressions on 9/6/2026 6:55:28 PM +00:00

Description

Contributor guide

Research direction

Assessment

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