[Perf] Linux/x64: 5 Regressions on 7/23/2026 1:41:19 PM +00:00

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#77,102 opened on Jul 30, 2026 2 comments 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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Forks: 8
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Description

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [026096b77a9dcfe0368a5d04d6fdc28efc3865d1](https://github.com/dotnet/runtime/commit/026096b77a9dcfe0368a5d04d6fdc28efc3865d1)
Compare | [54549c8df1cdbd7b373b56a53104439e75bcfcbd](https://github.com/dotnet/runtime/commit/54549c8df1cdbd7b373b56a53104439e75bcfcbd)
Diff | [Diff](https://github.com/dotnet/runtime/compare/026096b77a9dcfe0368a5d04d6fdc28efc3865d1...54549c8df1cdbd7b373b56a53104439e75bcfcbd)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Regressions in System.Memory.ReadOnlySequence

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

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

| 53.57 ns | 61.64 ns | 1.15 | 0.14 | False | | |
|

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

| 222.06 ns | 255.27 ns | 1.15 | 0.09 | 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_Start_And_Length(Segment: Multiple)

#### ETL Files

#### Histogram

#### JIT Disasms

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

#### 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.Collections.Perf_LengthBucketsFrozenDictionary

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

[TryGetValue_True_FrozenDictionary - Duration of single invocation]()
[ADX - Test Multi Config Graph]()

| 349.16 ns | 433.76 ns | 1.24 | 0.08 | 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.Perf_LengthBucketsFrozenDictionary*'
```

### System.Collections.Perf_LengthBucketsFrozenDictionary.TryGetValue_True_FrozenDictionary(Count: 10, ItemsPerBucket: 5)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Buffers.Tests.ReadOnlySequenceTests<Char>

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]()

| 52.13 ns | 59.45 ns | 1.14 | 0.08 | 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.Buffers.Tests.ReadOnlySequenceTests*'
```

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

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

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

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

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

| 1.18 μs | 1.40 μs | 1.19 | 0.06 | 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.IndexerSet*'
```

### System.Collections.IndexerSet<String>.Array(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

Contributor guide

No contributing guide indexed for this repository

Research direction

Start with the listed benchmark sources in dotnet/performance, including src/benchmarks/micro/libraries/System.Memory/ReadOnlySequence.cs and src/benchmarks/micro/libraries/System.Buffers/ReadOnlySequenceTests.cs, then compare the baseline and test reports. Run the provided benchmarks_ci.py filters and inspect the linked regression reports. 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: python, wasm
Domain: performance
Issue type: Bug
Difficulty: 4/5
Estimated time: 3-5 days
Activity status: Quiet
Clarity: Mostly clear
Newbie friendliness: 35/100

[Perf] Linux/x64: 5 Regressions on 7/23/2026 1:41:19 PM +00:00

Description

Contributor guide

Research direction

Assessment

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