[Perf] Linux/x64: 13 Regressions on 7/30/2026 2:24:29 PM +00:00

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#77,445 opened on Aug 6, 2026 1 comment 0 reactions 0 assignees View on GitHub

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

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Description

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [d1d60b31914b2a81a755890fad31cb44ca5cf5cd](https://github.com/dotnet/runtime/commit/d1d60b31914b2a81a755890fad31cb44ca5cf5cd)
Compare | [974b4b56b05ffe12857f731320f4b235bf36169c](https://github.com/dotnet/runtime/commit/974b4b56b05ffe12857f731320f4b235bf36169c)
Diff | [Diff](https://github.com/dotnet/runtime/compare/d1d60b31914b2a81a755890fad31cb44ca5cf5cd...974b4b56b05ffe12857f731320f4b235bf36169c)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Regressions in System.Tests.Perf_Int128

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

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

| 162.71 ns | 186.17 ns | 1.14 | 0.03 | False | | |
|

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

| 187.78 ns | 214.60 ns | 1.14 | 0.03 | False | | |
|

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

| 175.59 ns | 199.36 ns | 1.14 | 0.03 | False | | |
|

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

| 176.62 ns | 200.05 ns | 1.13 | 0.06 | 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_Int128*'
```

### System.Tests.Perf_Int128.TryFormat(value: 170141183460469231731687303715884105727)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_Int128.ToString(value: -170141183460469231731687303715884105728)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_Int128.ToString(value: 170141183460469231731687303715884105727)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_Int128.TryFormat(value: -170141183460469231731687303715884105728)

#### 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.Buffers.Tests.ReadOnlySequenceTests<Byte>

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

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

| 52.20 ns | 63.89 ns | 1.22 | 0.07 | False | | |
|

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

| 51.63 ns | 59.07 ns | 1.14 | 0.08 | False | | |
|

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

| 55.70 ns | 63.71 ns | 1.14 | 0.05 | 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.Buffers.Tests.ReadOnlySequenceTests*'
```

### System.Buffers.Tests.ReadOnlySequenceTests<Byte>.SliceSingleSegment

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Buffers.Tests.ReadOnlySequenceTests<Byte>.SliceArray

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Buffers.Tests.ReadOnlySequenceTests<Byte>.SliceMemory

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Memory.ReadOnlySequence

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

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

| 178.17 ns | 215.78 ns | 1.21 | 0.14 | False | | |
|

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

| 39.22 ns | 46.32 ns | 1.18 | 0.08 | 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.Memory.ReadOnlySequence*'
```

### System.Memory.ReadOnlySequence.Slice_Repeat(Segment: Single)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Memory.ReadOnlySequence.Slice_Start_And_Length(Segment: Single)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Collections.IterateFor<Int32>

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

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

| 4.21 μs | 4.44 μs | 1.05 | 0.04 | 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.IterateFor*'
```

### System.Collections.IterateFor<Int32>.IList(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Collections.TryGetValueFalse<SmallClass, SmallClass>

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

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

| 11.99 μs | 12.69 μs | 1.06 | 0.10 | 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.TryGetValueFalse*'
```

### System.Collections.TryGetValueFalse<SmallClass, SmallClass>.FrozenDictionaryOptimized(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Collections.ContainsKeyFalse<Int32, Int32>

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

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

| 11.57 μs | 12.71 μs | 1.10 | 0.09 | 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.ContainsKeyFalse*'
```

### System.Collections.ContainsKeyFalse<Int32, Int32>.IDictionary(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Numerics.Tests.Perf_VectorConvert

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

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

| 10.85 μs | 12.83 μs | 1.18 | 0.11 | 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.Numerics.Tests.Perf_VectorConvert*'
```

### System.Numerics.Tests.Perf_VectorConvert.Convert_double_long

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

Contributor guide

No contributing guide indexed for this repository

Research direction

Start by running the documented benchmarks_ci.py command with the System.Tests.Perf_Int128 filter, then compare the baseline and compare commits and review the linked performance reports. Inspect the benchmark sources at performance/src/benchmarks/micro/libraries/System.Runtime/Perf.Int128.cs and System.Buffers/ReadOnlySequenceTests.cs; done means the reported regressions are explained and the affected benchmarks no longer regress.

Written by the indexing model from the issue text.

Assessment

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

[Perf] Linux/x64: 13 Regressions on 7/30/2026 2:24:29 PM +00:00

Description

Contributor guide

Research direction

Assessment

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