[Perf] Windows/x86: 6 Regressions on 2/28/2026 9:09:22 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x86
OS | Windows 10.0.22631
Queue | ViperWindows
Baseline | [3176283d96819946eff7a6ddc65e88b52d4257e7](https://github.com/dotnet/runtime/commit/3176283d96819946eff7a6ddc65e88b52d4257e7)
Compare | [1d9d70afa98a83699719b304148a9945d37d916b](https://github.com/dotnet/runtime/commit/1d9d70afa98a83699719b304148a9945d37d916b)
Diff | [Diff](https://github.com/dotnet/runtime/compare/3176283d96819946eff7a6ddc65e88b52d4257e7...1d9d70afa98a83699719b304148a9945d37d916b)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.IO.Tests.Perf_FileStream

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

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

| 683.07 μs | 954.61 μs | 1.40 | 0.55 | False | | |
|

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

| 17.05 μs | 21.89 μs | 1.28 | 0.01 | False | | |
|

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

| 14.91 ns | 20.25 ns | 1.36 | 0.07 | False | | |
|

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

| 19.19 μs | 24.63 μs | 1.28 | 0.02 | False | | |
|

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

| 19.11 μs | 25.17 μs | 1.32 | 0.00 | False | | |
|

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

| 21.82 μs | 29.37 μs | 1.35 | 0.02 | False | | |

[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.IO.Tests.Perf_FileStream*'
```

### System.IO.Tests.Perf_FileStream.Write_NoBuffering(fileSize: 1048576, userBufferSize: 16384, options: Asynchronous)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.Perf_FileStream.SeekForward(fileSize: 1024, options: None)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.Perf_FileStream.GetLength(options: Read)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.Perf_FileStream.SeekBackward(fileSize: 1024, options: None)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.Perf_FileStream.SeekForward(fileSize: 1024, options: Asynchronous)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.Perf_FileStream.SeekBackward(fileSize: 1024, options: Asynchronous)

#### 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)