dotnet / dotnet/perf-autofiling-issues

[Perf] Linux/arm64: 67 Regressions on 8/5/2026 1:23:13 AM +00:00

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ampere arch-arm64 bdn-update branch-refs/heads/main compilationmode-tiered kind-micro Look Again os-linux perf-regression runkind-micro runtime-coreclr untriaged
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Description

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | ubuntu 22.04
Queue | AmpereUbuntu
Baseline | [2dd5330804f9d4f49599d82c90a67892d4dd8af0](https://github.com/dotnet/runtime/commit/2dd5330804f9d4f49599d82c90a67892d4dd8af0)
Compare | [c8f97975ab0d8ff84aebf176829e17f7c7052f03](https://github.com/dotnet/runtime/commit/c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Diff | [Diff](https://github.com/dotnet/runtime/compare/2dd5330804f9d4f49599d82c90a67892d4dd8af0...c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.IO.Tests.StreamReaderReadToEndTests

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

  • [ReadToEndAsync - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 71.19 ms | 80.92 ms | 1.14 | 0.02 | False | | |
|
  • [ReadToEndAsync - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 72.55 ms | 81.77 ms | 1.13 | 0.02 | False | | |
|
  • [ReadToEnd - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 72.65 ms | 81.55 ms | 1.12 | 0.01 | False | | |
|
  • [ReadToEnd - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 71.86 ms | 80.36 ms | 1.12 | 0.01 | False | | |
|
  • [ReadToEnd - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 76.21 ms | 84.31 ms | 1.11 | 0.01 | False | | |
|
  • [ReadToEndAsync - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 74.59 ms | 81.89 ms | 1.10 | 0.02 | False | | |
|
  • [ReadToEndAsync - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 76.32 ms | 83.59 ms | 1.10 | 0.03 | False | | |
|
  • [ReadToEnd - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 73.95 ms | 79.98 ms | 1.08 | 0.02 | False | | |
|
  • [ReadToEndAsync - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 73.03 ms | 78.56 ms | 1.08 | 0.02 | False | | |
|
  • [ReadToEnd - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 72.31 ms | 77.59 ms | 1.07 | 0.02 | False | | |
|
  • [ReadToEndAsync - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 75.71 ms | 80.69 ms | 1.07 | 0.01 | False | | |
|
  • [ReadToEnd - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 72.82 ms | 77.56 ms | 1.07 | 0.02 | False | | |
|
  • [ReadToEnd - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 74.51 ms | 79.17 ms | 1.06 | 0.01 | False | | |

![graph]()
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![graph]()
![graph]()
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[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.StreamReaderReadToEndTests*'
```

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEndAsync(LineLengthRange: [ 129, 1024])

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEndAsync(LineLengthRange: [ 33, 128])

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEnd(LineLengthRange: [ 9, 32])

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEnd(LineLengthRange: [ 129, 1024])

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEnd(LineLengthRange: [ 0, 0])

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEndAsync(LineLengthRange: [ 9, 32])

#### ETL Files

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#### JIT Disasms

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEndAsync(LineLengthRange: [ 0, 0])

#### ETL Files

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#### JIT Disasms

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEnd(LineLengthRange: [ 1, 1])

#### ETL Files

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### System.IO.Tests.StreamReaderReadToEndTests.ReadToEndAsync(LineLengthRange: [ 0, 1024])

#### ETL Files

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#### JIT Disasms

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEnd(LineLengthRange: [1025, 2048])

#### ETL Files

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### System.IO.Tests.StreamReaderReadToEndTests.ReadToEndAsync(LineLengthRange: [ 1, 8])

#### ETL Files

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#### JIT Disasms

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEnd(LineLengthRange: [ 33, 128])

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.StreamReaderReadToEndTests.ReadToEnd(LineLengthRange: [ 1, 8])

#### 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 | ubuntu 22.04
Queue | AmpereUbuntu
Baseline | [2dd5330804f9d4f49599d82c90a67892d4dd8af0](https://github.com/dotnet/runtime/commit/2dd5330804f9d4f49599d82c90a67892d4dd8af0)
Compare | [c8f97975ab0d8ff84aebf176829e17f7c7052f03](https://github.com/dotnet/runtime/commit/c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Diff | [Diff](https://github.com/dotnet/runtime/compare/2dd5330804f9d4f49599d82c90a67892d4dd8af0...c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in SeekUnroll

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

  • [Test - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 1.67 secs | 5.49 secs | 3.28 | 0.00 | False | | |
|
  • [Test - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 1.67 secs | 5.47 secs | 3.27 | 0.00 | False | | |
|
  • [Test - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 1.67 secs | 5.47 secs | 3.27 | 0.00 | False | | |
|
  • [Test - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 1.67 secs | 5.22 secs | 3.12 | 0.00 | False | | |
|
  • [Test - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 1.95 secs | 5.88 secs | 3.01 | 0.39 | False | | |

![graph]()
![graph]()
![graph]()
![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 'SeekUnroll*'
```

### SeekUnroll.Test(boxedIndex: 3)

#### ETL Files

#### Histogram

#### JIT Disasms

### SeekUnroll.Test(boxedIndex: 1)

#### ETL Files

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### SeekUnroll.Test(boxedIndex: 19)

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### SeekUnroll.Test(boxedIndex: 27)

#### ETL Files

#### Histogram

#### JIT Disasms

### SeekUnroll.Test(boxedIndex: 11)

#### 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 | ubuntu 22.04
Queue | AmpereUbuntu
Baseline | [2dd5330804f9d4f49599d82c90a67892d4dd8af0](https://github.com/dotnet/runtime/commit/2dd5330804f9d4f49599d82c90a67892d4dd8af0)
Compare | [c8f97975ab0d8ff84aebf176829e17f7c7052f03](https://github.com/dotnet/runtime/commit/c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Diff | [Diff](https://github.com/dotnet/runtime/compare/2dd5330804f9d4f49599d82c90a67892d4dd8af0...c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in Burgers

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

  • [Test1 - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 292.01 ms | 3640.32 ms | 12.47 | 0.00 | False | | |
|
  • [Test0 - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 354.37 ms | 3705.92 ms | 10.46 | 0.00 | False | | |
|
  • [Test3 - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 441.44 ms | 1464.32 ms | 3.32 | 0.00 | False | | |
|
  • [Test2 - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 293.40 ms | 944.97 ms | 3.22 | 0.00 | False | | |

![graph]()
![graph]()
![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 'Burgers*'
```

### Burgers.Test1

#### ETL Files

#### Histogram

#### JIT Disasms

### Burgers.Test0

#### ETL Files

#### Histogram

#### JIT Disasms

### Burgers.Test3

#### ETL Files

#### Histogram

#### JIT Disasms

### Burgers.Test2

#### 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 | ubuntu 22.04
Queue | AmpereUbuntu
Baseline | [2dd5330804f9d4f49599d82c90a67892d4dd8af0](https://github.com/dotnet/runtime/commit/2dd5330804f9d4f49599d82c90a67892d4dd8af0)
Compare | [c8f97975ab0d8ff84aebf176829e17f7c7052f03](https://github.com/dotnet/runtime/commit/c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Diff | [Diff](https://github.com/dotnet/runtime/compare/2dd5330804f9d4f49599d82c90a67892d4dd8af0...c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in LinqBenchmarks

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

  • [Count00ForX - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 85.19 ms | 673.92 ms | 7.91 | 0.00 | False | | |
|
  • [Where00ForX - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 174.82 ms | 856.40 ms | 4.90 | 0.20 | False | | |
|
  • [Where01ForX - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 124.00 ms | 405.64 ms | 3.27 | 0.00 | False | | |
|
  • [CountBy00LookupX - Duration of single invocation]()
  • ๐Ÿ“ - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 4.06 secs | 4.82 secs | 1.19 | 0.26 | False | | |

![graph]()
![graph]()
![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 'LinqBenchmarks*'
```

### LinqBenchmarks.Count00ForX

#### ETL Files

#### Histogram

#### JIT Disasms

### LinqBenchmarks.Where00ForX

#### ETL Files

#### Histogram

#### JIT Disasms

### LinqBenchmarks.Where01ForX

#### ETL Files

#### Histogram

#### JIT Disasms

### LinqBenchmarks.CountBy00LookupX

#### 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 | ubuntu 22.04
Queue | AmpereUbuntu
Baseline | [2dd5330804f9d4f49599d82c90a67892d4dd8af0](https://github.com/dotnet/runtime/commit/2dd5330804f9d4f49599d82c90a67892d4dd8af0)
Compare | [c8f97975ab0d8ff84aebf176829e17f7c7052f03](https://github.com/dotnet/runtime/commit/c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Diff | [Diff](https://github.com/dotnet/runtime/compare/2dd5330804f9d4f49599d82c90a67892d4dd8af0...c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Tests.Perf_GC<Char>

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

  • [AllocateUninitializedArray - Duration of single invocation]()
  • [ADX - Test Multi Config Graph]()
| 4.21 ฮผs | 5.16 ฮผs | 1.22 | 0.11 | False | | |
|
  • [AllocateArray - Duration of single invocation]()
  • [ADX - Test Multi Config Graph]()
| 4.20 ฮผs | 5.10 ฮผs | 1.22 | 0.09 | False | | |
|
  • [AllocateArray - Duration of single invocation]()
  • [ADX - Test Multi Config Graph]()
| 1.05 ฮผs | 1.14 ฮผs | 1.09 | 0.04 | False | | |
|
  • [AllocateArray - Duration of single invocation]()
  • [ADX - Test Multi Config Graph]()
| 140.76 ns | 150.85 ns | 1.07 | 0.03 | False | | |

![graph]()
![graph]()
![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.Tests.Perf_GC*'
```

### System.Tests.Perf_GC<Char>.AllocateUninitializedArray(length: 10000, pinned: True)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_GC<Char>.AllocateArray(length: 10000, pinned: True)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_GC<Char>.AllocateArray(length: 1000, pinned: True)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_GC<Char>.AllocateArray(length: 1000, pinned: False)

#### 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 | ubuntu 22.04
Queue | AmpereUbuntu
Baseline | [2dd5330804f9d4f49599d82c90a67892d4dd8af0](https://github.com/dotnet/runtime/commit/2dd5330804f9d4f49599d82c90a67892d4dd8af0)
Compare | [c8f97975ab0d8ff84aebf176829e17f7c7052f03](https://github.com/dotnet/runtime/commit/c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Diff | [Diff](https://github.com/dotnet/runtime/compare/2dd5330804f9d4f49599d82c90a67892d4dd8af0...c8f97975ab0d8ff84aebf176829e17f7c7052f03)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Tests.Perf_GC<Byte>

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

  • [AllocateUninitializedArray - Duration of single invocation]()
  • [ADX - Test Multi Config Graph]()
| 2.82 ฮผs | 3.28 ฮผs | 1.16 | 0.09 | False | | |
|
  • [AllocateArray - Duration of single invocation]()
  • [ADX - Test Multi Config Graph]()
| 2.86 ฮผs | 3.32 ฮผs | 1.16 | 0.10 | False | | |
|
  • [AllocateUninitializedArray - Duration of single invocation]()
  • [ADX - Test Multi Config Graph]()
| 579.80 ns | 634.59 ns | 1.09 | 0.03 | False | | |

![graph]()
![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.Tests.Perf_GC*'
```

### System.Tests.Perf_GC<Byte>.AllocateUninitializedArray(length: 10000, pinned: True)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_GC<Byte>.AllocateArray(length: 10000, pinned: True)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_GC<Byte>.AllocateUninitializedArray(length: 1000, pinned: True)

#### 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)

Contributor guide

No contributing guide indexed for this repository

Research direction

Start with the linked benchmark source, src/benchmarks/micro/libraries/System.IO/StreamReaderReadToEndTests.cs, especially lines 30-47, and compare the baseline and comparison commits. Run or inspect the affected ReadToEnd and ReadToEndAsync benchmark reports on Linux/arm64. Done means identifying the cause of the reported regressions and validating the resulting performance change.

Written by the indexing model from the issue text.

Assessment

Tech stack
linux, ubuntu
Domain
operating-systems, performance
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Quiet
Clarity
Needs clarification
Newbie friendliness
25/100

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