[Perf] Linux/x64: 20 Regressions on 7/10/2026 10:12:10 PM +00:00

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#76,383 opened on Jul 16, 2026 1 comment 0 reactions 0 assignees View on GitHub

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

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Description

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [99eb16b5420fe88e333e2d95600b8617a86d54ff](https://github.com/dotnet/runtime/commit/99eb16b5420fe88e333e2d95600b8617a86d54ff)
Compare | [26b900856a2f12c4c7126827cb3019accba8f17c](https://github.com/dotnet/runtime/commit/26b900856a2f12c4c7126827cb3019accba8f17c)
Diff | [Diff](https://github.com/dotnet/runtime/compare/99eb16b5420fe88e333e2d95600b8617a86d54ff...26b900856a2f12c4c7126827cb3019accba8f17c)
Configs | CompilationMode:wasm, RunKind:micro, RuntimeType:coreclr

### Regressions in System.Text.RegularExpressions.Tests.Perf_Regex_Common

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

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

| 56.79 μs | 71.53 μs | 1.26 | 0.24 | False | | |
|

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

| 6.54 ms | 7.76 ms | 1.19 | 0.42 | False | | |
|

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

| 21.25 μs | 22.47 μs | 1.06 | 0.39 | 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.Text.RegularExpressions.Tests.Perf_Regex_Common*'
```

### System.Text.RegularExpressions.Tests.Perf_Regex_Common.MatchWord(Options: IgnoreCase, Compiled)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.RegularExpressions.Tests.Perf_Regex_Common.MatchesSet(Options: Compiled)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.RegularExpressions.Tests.Perf_Regex_Common.Email_IsMatch(Options: IgnoreCase, Compiled)

#### 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.Text.RegularExpressions.Tests.Perf_Regex_Cache

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

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

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

[IsMatch - Duration of single invocation]()
📝 - [Benchmark Source]()
[ADX - Test Multi Config 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.RegularExpressions.Tests.Perf_Regex_Cache*'
```

### System.Text.RegularExpressions.Tests.Perf_Regex_Cache.IsMatch(total: 40000, unique: 7, cacheSize: 0)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.RegularExpressions.Tests.Perf_Regex_Cache.IsMatch(total: 40000, unique: 1600, cacheSize: 800)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Text.RegularExpressions.Tests.Perf_Regex_Cache.IsMatch(total: 40000, unique: 1600, cacheSize: 15)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in GuardedDevirtualization.ThreeClassVirtual

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

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

| 44.79 ns | 62.16 ns | 1.39 | 0.31 | False | | |
|

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

| 51.50 ns | 67.60 ns | 1.31 | 0.27 | False | | |
|

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

| 48.12 ns | 55.39 ns | 1.15 | 0.24 | 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 'GuardedDevirtualization.ThreeClassVirtual*'
```

### GuardedDevirtualization.ThreeClassVirtual.Call(testInput: pB=0.33 pD=0.33)

#### ETL Files

#### Histogram

#### JIT Disasms

### GuardedDevirtualization.ThreeClassVirtual.Call(testInput: pB=0.67 pD=0.00)

#### ETL Files

#### Histogram

#### JIT Disasms

### GuardedDevirtualization.ThreeClassVirtual.Call(testInput: pB=0.67 pD=0.33)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Tests.Perf_String

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

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

| 499.04 ns | 614.94 ns | 1.23 | 0.48 | False | | |
|

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

| 375.36 ns | 398.36 ns | 1.06 | 0.46 | 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.Tests.Perf_String*'
```

### System.Tests.Perf_String.Trim_CharArr(s: "Test", c: [' ', ' '])

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Tests.Perf_String.TrimEnd_CharArr(s: "Test", c: [' ', ' '])

#### 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]()

| 35.24 μs | 44.65 μs | 1.27 | 0.20 | False | | |
|

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

| 12.96 μs | 15.60 μs | 1.20 | 0.58 | 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.IterateFor*'
```

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

#### ETL Files

#### Histogram

#### JIT Disasms

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

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in ByteMark

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

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

[BenchEmFloatClass - Duration of single invocation]()
📝 - [Benchmark Source]()
[ADX - Test Multi Config 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 'ByteMark*'
```

### ByteMark.BenchNumericSortJagged

#### ETL Files

#### Histogram

#### JIT Disasms

### ByteMark.BenchEmFloatClass

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in Microsoft.Extensions.Primitives.StringSegmentBenchmark

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

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

| 2.96 μs | 3.82 μs | 1.29 | 0.36 | 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 'Microsoft.Extensions.Primitives.StringSegmentBenchmark*'
```

### Microsoft.Extensions.Primitives.StringSegmentBenchmark.GetSegmentHashCode

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in Benchstone.BenchI.BubbleSort2

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]()

![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.BenchI.BubbleSort2*'
```

### Benchstone.BenchI.BubbleSort2.Test

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Text.Encodings.Web.Tests.Perf_Encoders

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

[EncodeUtf16 - Duration of single invocation]()
📝 - [Benchmark Source]()
[ADX - Test Multi Config Graph]()

| 7.49 μs | 8.02 μs | 1.07 | 0.26 | 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.Text.Encodings.Web.Tests.Perf_Encoders*'
```

### System.Text.Encodings.Web.Tests.Perf_Encoders.EncodeUtf16(arguments: UnsafeRelaxed,no <escaping /> required,16)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.IO.Tests.MemoryStreamChunkedTests

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

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

| 14.26 ms | 17.43 ms | 1.22 | 0.53 | 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.MemoryStreamChunkedTests*'
```

### System.IO.Tests.MemoryStreamChunkedTests.ReadByteArray(ChunkSize: 1)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

---

### Run Information

### Regressions in System.Net.Primitives.Tests.CredentialCacheTests

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

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

| 7.91 μs | 9.12 μs | 1.15 | 0.25 | 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.Net.Primitives.Tests.CredentialCacheTests*'
```

### System.Net.Primitives.Tests.CredentialCacheTests.GetCredential_HostPort(host: "name5", hostPortCount: 10)

#### ETL Files

#### Histogram

#### JIT Disasms

### Docs

Contributor guide

No contributing guide indexed for this repository

Research direction

Start with the listed benchmark sources, src/benchmarks/micro/libraries/System.Text.RegularExpressions/Perf.Regex.Common.cs and Perf.Regex.Cache.cs, then run the benchmarks_ci.py command from the reproduction section. Compare the baseline and test commits, inspect the linked reports, and determine what accounts for the reported regressions; done means the regression is explained and addressed or escalated with evidence.

Written by the indexing model from the issue text.

Assessment

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

[Perf] Linux/x64: 20 Regressions on 7/10/2026 10:12:10 PM +00:00

Description

Contributor guide

Research direction

Assessment

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