dotnet / dotnet/perf-autofiling-issues

[Perf] Linux/arm64: 6 Regressions on 7/17/2026 10:18:08 PM +00:00

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

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [09f41d9272e6dcff30bfa15653e124d013167e05](https://github.com/dotnet/runtime/commit/09f41d9272e6dcff30bfa15653e124d013167e05)
Compare | [e7c3d6567c4d78e0c10627fa89939767464478c2](https://github.com/dotnet/runtime/commit/e7c3d6567c4d78e0c10627fa89939767464478c2)
Diff | [Diff](https://github.com/dotnet/runtime/compare/09f41d9272e6dcff30bfa15653e124d013167e05...e7c3d6567c4d78e0c10627fa89939767464478c2)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Collections.Perf_Frozen<NotKnownComparable>

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

  • [ToFrozenDictionary - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 30.36 μs | 38.17 μs | 1.26 | 0.13 | False | | |
|
  • [ToFrozenDictionary - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 3.24 μs | 3.93 μs | 1.21 | 0.22 | 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
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Collections.Perf_Frozen*'
```

### System.Collections.Perf_Frozen<NotKnownComparable>.ToFrozenDictionary(Count: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Collections.Perf_Frozen<NotKnownComparable>.ToFrozenDictionary(Count: 64)

#### 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 | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [09f41d9272e6dcff30bfa15653e124d013167e05](https://github.com/dotnet/runtime/commit/09f41d9272e6dcff30bfa15653e124d013167e05)
Compare | [e7c3d6567c4d78e0c10627fa89939767464478c2](https://github.com/dotnet/runtime/commit/e7c3d6567c4d78e0c10627fa89939767464478c2)
Diff | [Diff](https://github.com/dotnet/runtime/compare/09f41d9272e6dcff30bfa15653e124d013167e05...e7c3d6567c4d78e0c10627fa89939767464478c2)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Buffers.Tests.RentReturnArrayPoolTests<Object>

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

  • [SingleSerial - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 13.51 ns | 24.16 ns | 1.79 | 0.22 | False | | |
|
  • [SingleParallel - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 17.15 ns | 27.63 ns | 1.61 | 0.47 | 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
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Buffers.Tests.RentReturnArrayPoolTests*'
```

### System.Buffers.Tests.RentReturnArrayPoolTests<Object>.SingleSerial(RentalSize: 4096, ManipulateArray: False, Async: False, UseSharedPool: True)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Buffers.Tests.RentReturnArrayPoolTests<Object>.SingleParallel(RentalSize: 4096, ManipulateArray: False, Async: False, UseSharedPool: 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)

---

### Run Information

Name | Value
-- | --
Architecture | arm64
OS | azurelinux 3.0
Queue | CobaltAzureLinux
Baseline | [09f41d9272e6dcff30bfa15653e124d013167e05](https://github.com/dotnet/runtime/commit/09f41d9272e6dcff30bfa15653e124d013167e05)
Compare | [e7c3d6567c4d78e0c10627fa89939767464478c2](https://github.com/dotnet/runtime/commit/e7c3d6567c4d78e0c10627fa89939767464478c2)
Diff | [Diff](https://github.com/dotnet/runtime/compare/09f41d9272e6dcff30bfa15653e124d013167e05...e7c3d6567c4d78e0c10627fa89939767464478c2)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Collections.Perf_Frozen<Int16>

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

  • [ToFrozenDictionary - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 27.04 μs | 34.84 μs | 1.29 | 0.17 | False | | |
|
  • [ToFrozenDictionary - Duration of single invocation]()
  • 📝 - [Benchmark Source]()
  • [ADX - Test Multi Config Graph]()
| 2.95 μs | 3.55 μs | 1.20 | 0.26 | 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
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Collections.Perf_Frozen*'
```

### System.Collections.Perf_Frozen<Int16>.ToFrozenDictionary(Count: 512)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Collections.Perf_Frozen<Int16>.ToFrozenDictionary(Count: 64)

#### 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 benchmark sources src/benchmarks/micro/libraries/System.Collections/Frozen/Perf_Frozen.cs and src/benchmarks/micro/libraries/System.Buffers/ArrayPoolTests.cs, then compare the linked baseline and test reports for the arm64 AzureLinux run. Use scripts/benchmarks_ci.py with the provided filters to reproduce the reported regressions. Done means identifying and addressing the cause of the listed performance regressions and confirming the benchmarks no longer regress.

Written by the indexing model from the issue text.

Assessment

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

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