[Perf] Linux/x64: 5 Regressions on 8/26/2026 4:02:35 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [519e88bf80b5d39bc2c4e788a025a499136a1661](https://github.com/dotnet/runtime/commit/519e88bf80b5d39bc2c4e788a025a499136a1661)
Compare | [08df03ba6493589f3816e193847b50f105bf4c7a](https://github.com/dotnet/runtime/commit/08df03ba6493589f3816e193847b50f105bf4c7a)
Diff | [Diff](https://github.com/dotnet/runtime/compare/519e88bf80b5d39bc2c4e788a025a499136a1661...08df03ba6493589f3816e193847b50f105bf4c7a)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Diagnostics.Perf_Process

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

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

| 1.14 μs | 1.57 μs | 1.38 | 0.03 | False | | |
|

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

| 811.32 μs | 892.11 μs | 1.10 | 0.15 | 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.Diagnostics.Perf_Process*'
```

### System.Diagnostics.Perf_Process.GetProcessById

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Diagnostics.Perf_Process.StartAndWaitForExit

#### 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 | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [8baacb006f5615ebd705bdf9de98ca5df7bf1ba1](https://github.com/dotnet/runtime/commit/8baacb006f5615ebd705bdf9de98ca5df7bf1ba1)
Compare | [08df03ba6493589f3816e193847b50f105bf4c7a](https://github.com/dotnet/runtime/commit/08df03ba6493589f3816e193847b50f105bf4c7a)
Diff | [Diff](https://github.com/dotnet/runtime/compare/8baacb006f5615ebd705bdf9de98ca5df7bf1ba1...08df03ba6493589f3816e193847b50f105bf4c7a)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Buffers.Text.Tests.Utf8FormatterTests

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

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

| 14.15 ns | 18.79 ns | 1.33 | 0.01 | False | | |
|

• [FormatterInt64 - Duration of single invocation]()
• 📝 - [Benchmark Source]()
• [ADX - Test Multi Config Graph]()

| 12.61 ns | 13.73 ns | 1.09 | 0.01 | 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.Buffers.Text.Tests.Utf8FormatterTests*'
```

### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterDateTimeOffsetNow(value: 12/30/2017 3:45:22 AM -08:00)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Buffers.Text.Tests.Utf8FormatterTests.FormatterInt64(value: 9223372036854775807)

#### 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 | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [519e88bf80b5d39bc2c4e788a025a499136a1661](https://github.com/dotnet/runtime/commit/519e88bf80b5d39bc2c4e788a025a499136a1661)
Compare | [08df03ba6493589f3816e193847b50f105bf4c7a](https://github.com/dotnet/runtime/commit/08df03ba6493589f3816e193847b50f105bf4c7a)
Diff | [Diff](https://github.com/dotnet/runtime/compare/519e88bf80b5d39bc2c4e788a025a499136a1661...08df03ba6493589f3816e193847b50f105bf4c7a)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Tests.Perf_String

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

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

| 18.98 ns | 20.21 ns | 1.06 | 0.17 | 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_String*'
```

### System.Tests.Perf_String.Replace_String(text: "This is a very nice sentence. This is another very nice sentence.", oldValue: "a", newValue: "b")

#### 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)

Start with the linked baseline and compare commits, then read the benchmark sources at src/benchmarks/micro/libraries/System.Diagnostics/Perf_Process.cs, Utf8FormatterTests.cs, and Perf.String.cs. Run the listed benchmarks with benchmarks_ci.py and inspect the linked test reports and graphs. Done means identifying the cause of the five Linux/x64 regressions and validating the result against the affected benchmarks.

Written by the indexing model from the issue text.