microbenchmarks: add buffer rotation option

[matthiasdiener]

Description

Add a new option, --rotating-buffers, to rotate input buffers (off by default).
Follows the discussions in:

• https://docs.nvidia.com/cutlass/latest/media/docs/cpp/gemm_performance_measurement_methodology_guidelines.html
• https://amd.atlassian.net/wiki/spaces/MLSE/pages/744192648/hipBLASLt+Standard+Benchmarking

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Infra/Build change
• Code refactoring

Changes

Checklist:

• I have read and followed the contributing guidelines
• The functionality is complete
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[Copilot]

Pull request overview

Adds an opt-in --rotating-buffers mode to the microbenchmarks to cycle input tensors through a buffer ring, reducing artificial cache-residency effects and aligning measurements with common GEMM benchmarking methodology.

Changes:

• Introduces buffer-rotation utilities (rotating, make_input) and a new CLI flag --rotating-buffers [N] in the shared microbenchmark runner.
• Updates several benchmarks (GEMM, FP8 GEMM, normalization, grouped GEMM, casting) to use rotation-aware input construction.
• Documents the new option and usage examples in the microbenchmarks README.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
benchmarks/microbenchmarks/utils.py	Adds rotation machinery + CLI flag plumbing and helper APIs used by benchmarks.
benchmarks/microbenchmarks/README.md	Documents --rotating-buffers behavior and provides example invocations.
benchmarks/microbenchmarks/benchmark_normalization.py	Switches normalization benchmarks to rotation-aware input generation.
benchmarks/microbenchmarks/benchmark_grouped_gemm.py	Updates grouped GEMM benchmark to optionally follow rotated activation buffers.
benchmarks/microbenchmarks/benchmark_gemm.py	Switches GEMM benchmark to rotation-aware input generation.
benchmarks/microbenchmarks/benchmark_gemm_fp8.py	Switches FP8 GEMM benchmark to rotation-aware input generation.
benchmarks/microbenchmarks/benchmark_casting.py	Uses rotation-aware inputs for quantize path and rotates FP8 tensors for dequantize path.

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[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated no new comments.