[QST]Why Does CUTLASS Use 3-4-3 Swizzle?
Open
Nobody has claimed this yet.
? - Needs Triage
inactive-30d
inactive-90d
question
- Dominant language
- C++
- Stars
- 10.5k
- Forks
- 2.1k
- Avg merge
- 3d 11h
- Merged PRs (30d)
- 7
Description
May I kindly ask why the swizzle configuration in CUTLASS is specifically set to 3, 4, and 3? I would greatly appreciate any insights or explanations regarding the rationale behind this design choice. Thank you so much in advance!
// K-major GMMA layouts in units of bits
using Layout_K_INTER_Atom_Bits = ComposedLayout<Swizzle<0,4,3>, smem_ptr_flag, Layout<Shape<_8, _128>,Stride< _128,_1>>>;
using Layout_K_SW32_Atom_Bits = ComposedLayout<Swizzle<1,4,3>, smem_ptr_flag, Layout<Shape<_8, _256>,Stride< _256,_1>>>;
using Layout_K_SW64_Atom_Bits = ComposedLayout<Swizzle<2,4,3>, smem_ptr_flag, Layout<Shape<_8, _512>,Stride< _512,_1>>>;
using Layout_K_SW128_Atom_Bits = ComposedLayout<Swizzle<3,4,3>, smem_ptr_flag, Layout<Shape<_8,_1024>,Stride<_1024,_1>>>;
Contributor guide
No contributing guide indexed for this repository
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by tracing the four listed ComposedLayout and Swizzle configurations in the CUTLASS source, then read the surrounding layout and GMMA documentation. Determine whether the project explains why the 3-4-3 parameters and related K-major variants are chosen; done means recording that rationale in an appropriate documentation location.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- performance
- Issue type
- Documentation
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100