[WIP, Kernel] (1/N) Machete - Hopper Optimized Mixed Precision Linear Kernel

[LucasWilkinson]

Notes

This PR is a work in progress and based off of: vllm-project#6396 so that will have to land before this.

Description

This PR introduces a spiritual successor to the Marlin kernel but optimized for Hopper architectures and based off of cutlass.

Motivation

The motivation for this kernel is multifold:

1. Marlin (v1) uses mma instructions, which are fastest tensor core instructions available on Ampere but with Hopper Nvidia release a set of new wgmma instructions which are required to hit the peak FLOPs reported by Nvidia, without them i.e. using mma instructions you can expect to achieve at best ~75% of peak [1, 2]
2. Marlin (v1) uses a specific weight storage layout that is specialized for the mma instructions, we want to adopt a more flexible/dynamic way of defining these layouts so we can accommodate new instructions more rapidly, i.e. wgmma and new instructions Blackwell introduces if any
   • MarlinV2 achieves this by describing the weight storage scheme using cutlass and CUTE
3. Marlin (v1) does not support cutlass epilogues, we eventually plan to investigate subbyte weight quantization + activation quantization, for activation quantization we'd like to leverage the great work done by @tlrmchlsmth @varun-sundar-rabindranath and @ProExpertProg to write custom cutlass epilogues for fp8 and int8

TODO:

• Chose a new name (candidates: wahoo, swordfish (kinda cutlass + marlin), non-fish names ...): edit: chose machete
• Improve heuristic namely for 4096x4096
• Improve BFloat16 performance (via bit shift or interleaving)
• E2E integration (future PR)
• Improve batch size < 32 performance (potentially a future PR, likely through improving the stream-k scheduler)
• Investigate fp8 activation support (future PR)

Current Performance

Float16

BFloat16

[github-actions]

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[LucasWilkinson]

Migrated to: #401