[Perf] Linux/x64: 3 Regressions on 3/17/2026 4:11:41 PM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [fc529276b042443bd335adc6b5a26526e7ac9905](https://github.com/dotnet/runtime/commit/fc529276b042443bd335adc6b5a26526e7ac9905)
Compare | [c31475ea97de93297d055374284e1b1d4769332d](https://github.com/dotnet/runtime/commit/c31475ea97de93297d055374284e1b1d4769332d)
Diff | [Diff](https://github.com/dotnet/runtime/compare/fc529276b042443bd335adc6b5a26526e7ac9905...c31475ea97de93297d055374284e1b1d4769332d)
Configs | AOT:true, CompilationMode:wasm, RunKind:micro

### Regressions in System.IO.Tests.Perf_RandomAccess

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

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

| 1.42 ms | 1.53 ms | 1.08 | 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.IO.Tests.Perf_RandomAccess*'
```

### System.IO.Tests.Perf_RandomAccess.Write(fileSize: 1048576, bufferSize: 4096, 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)

---

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [fc529276b042443bd335adc6b5a26526e7ac9905](https://github.com/dotnet/runtime/commit/fc529276b042443bd335adc6b5a26526e7ac9905)
Compare | [c31475ea97de93297d055374284e1b1d4769332d](https://github.com/dotnet/runtime/commit/c31475ea97de93297d055374284e1b1d4769332d)
Diff | [Diff](https://github.com/dotnet/runtime/compare/fc529276b042443bd335adc6b5a26526e7ac9905...c31475ea97de93297d055374284e1b1d4769332d)
Configs | AOT:true, CompilationMode:wasm, 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]()

| 579.21 ms | 615.32 ms | 1.06 | 0.17 | False | | |
|

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

| 600.80 ms | 647.51 ms | 1.08 | 0.23 | 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.IO.Tests.Perf_FileStream*'
```

### System.IO.Tests.Perf_FileStream.Write_NoBuffering(fileSize: 104857600, userBufferSize: 16384, options: Asynchronous)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.IO.Tests.Perf_FileStream.Write(fileSize: 104857600, userBufferSize: 4096, 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)

Start with the benchmark sources named in dotnet/performance: src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.RandomAccess.cs and Perf.FileStream.cs, then run the provided benchmarks_ci.py filters. Compare the baseline and compare commits and inspect the linked reports to identify the regression. Done means the affected benchmarks no longer show the reported regression and the result is verified by rerunning them.

Written by the indexing model from the issue text.