dotnet / dotnet/perf-autofiling-issues

[Perf] Linux/x64: 102 Regressions on 8/25/2026 10:44:15 PM +00:00

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arch-wasm arch-x64 branch-refs/heads/main compilationmode-wasm kind-micro Look Again os-linux perf-regression runkind-micro runtimetype-coreclr untriaged
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Description

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [8baacb006f5615ebd705bdf9de98ca5df7bf1ba1](https://github.com/dotnet/runtime/commit/8baacb006f5615ebd705bdf9de98ca5df7bf1ba1)
Compare | [9f18a550aaa91ecd032ac024b67e03559df9e766](https://github.com/dotnet/runtime/commit/9f18a550aaa91ecd032ac024b67e03559df9e766)
Diff | [Diff](https://github.com/dotnet/runtime/compare/8baacb006f5615ebd705bdf9de98ca5df7bf1ba1...9f18a550aaa91ecd032ac024b67e03559df9e766)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in System.Buffers.Text.Tests.Utf8FormatterTests

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

  • [FormatterDateTimeOffsetNow - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 3.66 μs | 16.99 μs | 4.64 | 0.11 | False | | |
|
  • [FormatterUInt64 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 6.31 μs | 18.85 μs | 2.99 | 0.18 | False | | |
|
  • [FormatterInt64 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 5.73 μs | 16.96 μs | 2.96 | 0.18 | False | | |
|
  • [FormatterUInt32 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 3.73 μs | 11.03 μs | 2.96 | 0.17 | False | | |
|
  • [FormatterInt32 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 3.80 μs | 10.78 μs | 2.84 | 0.16 | False | | |
|
  • [FormatterInt64 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 6.90 μs | 18.26 μs | 2.65 | 0.20 | False | | |
|
  • [FormatterDecimal - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 16.47 μs | 37.97 μs | 2.31 | 0.20 | False | | |
|
  • [FormatterUInt32 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 2.73 μs | 5.61 μs | 2.06 | 0.13 | False | | |
|
  • [FormatterInt32 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 2.79 μs | 5.61 μs | 2.01 | 0.17 | False | | |
|
  • [FormatterInt64 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 2.96 μs | 5.83 μs | 1.97 | 0.15 | False | | |
|
  • [FormatterUInt64 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 2.95 μs | 5.76 μs | 1.95 | 0.12 | False | | |
|
  • [FormatterDouble - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 25.80 μs | 34.02 μs | 1.32 | 0.24 | False | | |
|
  • [FormatterDouble - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 24.92 μs | 31.64 μs | 1.27 | 0.22 | False | | |

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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.Buffers.Text.Tests.Utf8FormatterTests*'
```

### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterDateTimeOffsetNow(value: 12/30/2017 3:45:22 AM -08:00)

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#### Histogram

#### JIT Disasms

### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterUInt64(value: 18446744073709551615)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterInt64(value: 9223372036854775807)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterUInt32(value: 4294967295)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterInt32(value: 2147483647)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterInt64(value: -9223372036854775808)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterDecimal(value: 123456.78900000000430736690760)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterUInt32(value: 12345)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterInt32(value: 12345)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterInt64(value: 12345)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterUInt64(value: 12345)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterDouble(value: -1.7976931348623157E+308)

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### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterDouble(value: 1.7976931348623157E+308)

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### 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 | [8baacb006f5615ebd705bdf9de98ca5df7bf1ba1](https://github.com/dotnet/runtime/commit/8baacb006f5615ebd705bdf9de98ca5df7bf1ba1)
Compare | [9f18a550aaa91ecd032ac024b67e03559df9e766](https://github.com/dotnet/runtime/commit/9f18a550aaa91ecd032ac024b67e03559df9e766)
Diff | [Diff](https://github.com/dotnet/runtime/compare/8baacb006f5615ebd705bdf9de98ca5df7bf1ba1...9f18a550aaa91ecd032ac024b67e03559df9e766)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

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

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

  • [WriteBasicUtf16 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 399.43 ms | 626.14 ms | 1.57 | 0.13 | False | | |
|
  • [WriteBasicUtf8 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 401.63 ms | 629.23 ms | 1.57 | 0.18 | False | | |
|
  • [WriteBasicUtf16 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 398.46 ms | 624.22 ms | 1.57 | 0.18 | False | | |
|
  • [WriteBasicUtf8 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 396.84 ms | 617.91 ms | 1.56 | 0.16 | False | | |
|
  • [WriteBasicUtf8 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 492.74 ms | 750.84 ms | 1.52 | 0.18 | False | | |
|
  • [WriteBasicUtf16 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 480.60 ms | 708.42 ms | 1.47 | 0.23 | False | | |
|
  • [WriteBasicUtf8 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 488.05 ms | 702.50 ms | 1.44 | 0.21 | False | | |
|
  • [WriteBasicUtf16 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 494.14 ms | 709.86 ms | 1.44 | 0.16 | False | | |
|
  • [WriteBasicUtf16 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 118.40 μs | 147.70 μs | 1.25 | 0.14 | False | | |
|
  • [WriteBasicUtf16 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 147.84 μs | 181.95 μs | 1.23 | 0.15 | False | | |
|
  • [WriteBasicUtf8 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 133.78 μs | 161.49 μs | 1.21 | 0.18 | False | | |
|
  • [WriteBasicUtf8 - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 160.64 μs | 187.89 μs | 1.17 | 0.18 | False | | |

![graph]()
![graph]()
![graph]()
![graph]()
![graph]()
![graph]()
![graph]()
![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 'System.Text.Json.Tests.Perf_Basic*'
```

### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf16(Formatted: False, SkipValidation: False, DataSize: 100000)

#### ETL Files

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#### JIT Disasms

### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf8(Formatted: False, SkipValidation: False, DataSize: 100000)

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### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf16(Formatted: False, SkipValidation: True, DataSize: 100000)

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### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf8(Formatted: False, SkipValidation: True, DataSize: 100000)

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### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf8(Formatted: True, SkipValidation: False, DataSize: 100000)

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### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf16(Formatted: True, SkipValidation: False, DataSize: 100000)

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### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf8(Formatted: True, SkipValidation: True, DataSize: 100000)

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### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf16(Formatted: True, SkipValidation: True, DataSize: 100000)

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### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf16(Formatted: False, SkipValidation: True, DataSize: 10)

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### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf16(Formatted: True, SkipValidation: True, DataSize: 10)

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### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf8(Formatted: False, SkipValidation: True, DataSize: 10)

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### System.Text.Json.Tests.Perf_Basic.WriteBasicUtf8(Formatted: True, SkipValidation: True, DataSize: 10)

#### ETL Files

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#### 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 Utf8FormatterTests benchmark source in src/benchmarks/micro/libraries/System.Buffers/Utf8FormatterTests.cs and compare the baseline and test commits. Run the reported WASM microbenchmark configuration and inspect the linked history reports; done means the regression is explained and the affected benchmarks no longer show the reported slowdown.

Written by the indexing model from the issue text.

Assessment

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

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