[Perf] Linux/x64: 2 Regressions on 9/1/2026 5:28:08 AM +00:00

### Run Information

Name | Value
-- | --
Architecture | x64
OS | ubuntu 22.04
Queue | ViperUbuntu
Baseline | [ef3efe5e020e412e4f6453781d59443e975010a4](https://github.com/dotnet/runtime/commit/ef3efe5e020e412e4f6453781d59443e975010a4)
Compare | [818ad35699cf9b1a3e3f2067c133d8dbe599da2e](https://github.com/dotnet/runtime/commit/818ad35699cf9b1a3e3f2067c133d8dbe599da2e)
Diff | [Diff](https://github.com/dotnet/runtime/compare/ef3efe5e020e412e4f6453781d59443e975010a4...818ad35699cf9b1a3e3f2067c133d8dbe599da2e)
Configs | CompilationMode:tiered, RunKind:micro

### Regressions in System.Numerics.Tests.Perf_BigInteger

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

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

| 54.25 ns | 77.04 ns | 1.42 | 0.00 | False | | |
|

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

| 80.84 ns | 93.86 ns | 1.16 | 0.10 | 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.Numerics.Tests.Perf_BigInteger*'
```

### System.Numerics.Tests.Perf_BigInteger.ModPow(arguments: 16,16,16 bits)

#### ETL Files

#### Histogram

#### JIT Disasms

### System.Numerics.Tests.Perf_BigInteger.Add(arguments: 1024,1024 bits)

#### 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 src/benchmarks/micro/libraries/System.Runtime.Numerics/Perf.BigInteger.cs at the linked Add and ModPow benchmarks, then run the provided benchmarks_ci.py command. Compare the baseline and test commits and inspect the linked reports to identify the regression. Done means the cause is validated and the benchmark results are restored or the regression is documented for triage.

Written by the indexing model from the issue text.