[Perf] Linux/x64: 12 Regressions on 8/4/2026 8:53:30 PM +00:00

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#77,720 opened on Aug 11, 2026 1 comment 0 reactions 0 assignees View on GitHub

aot-true arch-wasm arch-x64 bdn-update 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 | [2dd5330804f9d4f49599d82c90a67892d4dd8af0](https://github.com/dotnet/runtime/commit/2dd5330804f9d4f49599d82c90a67892d4dd8af0)
Compare | [173e6b40e02cd1652102c09e07bd4cf7320b3d4d](https://github.com/dotnet/runtime/commit/173e6b40e02cd1652102c09e07bd4cf7320b3d4d)
Diff | [Diff](https://github.com/dotnet/runtime/compare/2dd5330804f9d4f49599d82c90a67892d4dd8af0...173e6b40e02cd1652102c09e07bd4cf7320b3d4d)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Regressions in System.Tests.Perf_Uri

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

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

| 1.45 μs | 1.71 μs | 1.18 | 0.05 | False | | |
|

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

| 1.34 μs | 1.42 μs | 1.06 | 0.05 | False | | |
|

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

| 1.46 μs | 1.55 μs | 1.06 | 0.06 | False | | |
|

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

| 1.40 μs | 1.48 μs | 1.06 | 0.05 | 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_Uri*'
```

### System.Tests.Perf_Uri.CtorIdnHostPathAndQuery(input: "http://dot.net/path/with?key=value#fragment")

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_Uri.CtorIdnHostPathAndQuery(input: "http://host/path?key1=value1&key2=value2&key3=value3&key4=value4")

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_Uri.CtorIdnHostPathAndQuery(input: "https://a.much.longer.domain.name/path/with?key=value#fragment")

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_Uri.CtorIdnHostPathAndQuery(input: "http://host/path%20with%20escapable%20values?key=va%20lue")

#### 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_SingleCharFrozenDictionary

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

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

| 887.74 μs | 954.98 μs | 1.08 | 0.09 | False | | |
|

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

| 8.98 μs | 9.53 μs | 1.06 | 0.05 | 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.Collections.Perf_SingleCharFrozenDictionary*'
```

### System.Collections.Perf_SingleCharFrozenDictionary.ToFrozenDictionary(Count: 10000)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Collections.Perf_SingleCharFrozenDictionary.ToFrozenDictionary(Count: 100)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.MathBenchmarks.Double

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

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

| 55.22 μs | 61.98 μs | 1.12 | 0.05 | 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.MathBenchmarks.Double*'
```

### System.MathBenchmarks.Double.FusedMultiplyAdd

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Tests.Perf_Int32

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

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

| 55.36 ns | 58.90 ns | 1.06 | 0.18 | 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.Tests.Perf_Int32*'
```

### System.Tests.Perf_Int32.ToStringHex(value: 4)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.IO.Tests.Perf_Path

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

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

| 68.51 ns | 72.67 ns | 1.06 | 0.13 | 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_Path*'
```

### System.IO.Tests.Perf_Path.GetDirectoryName

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in Benchstone.BenchF.BenchMk2

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

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

| 121.59 ms | 131.33 ms | 1.08 | 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 'Benchstone.BenchF.BenchMk2*'
```

### Benchstone.BenchF.BenchMk2.Test

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Tests.Perf_Random

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

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

| 4.85 μs | 7.08 μs | 1.46 | 0.41 | 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.Tests.Perf_Random*'
```

### System.Tests.Perf_Random.NextBytes_span

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

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

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

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

| 35.19 μs | 37.59 μs | 1.07 | 0.03 | 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.CtorFromCollectionNonGeneric*'
```

### System.Collections.CtorFromCollectionNonGeneric<String>.Hashtable(Size: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

Contributor guide

No contributing guide indexed for this repository

Research direction

Start with the linked baseline-to-compare Diff and the System.Tests.Perf_Uri and System.Collections.Perf_SingleCharFrozenDictionary benchmark entries. Reproduce the results with scripts/benchmarks_ci.py using the documented filter, then compare the reported benchmark output with the supplied reports. Done means explaining or addressing the reported regressions and validating the result.

Written by the indexing model from the issue text.

Assessment

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

[Perf] Linux/x64: 12 Regressions on 8/4/2026 8:53:30 PM +00:00

Description

Contributor guide

Research direction

Assessment

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