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composable_kernel/example/ck_tile
Jeff Huang 7c6430eca0 [CK_TILE] fmha: Add query padding support to backward pass (#3097)
* [CK_TILE] fmha: Add query padding support to backward pass

Introduces support for query sequence padding (q_padding) in the FMHA backward pass kernels.
- Passing `seqlen_q_ptr` to the backward kernels to distinguish logical from physical sequence lengths.
- Updating `OGradDotO`, `ConvertQGrad`, and `DQDKDV` kernels to respect logical lengths and handle zero-length sequences.
- Aligning LSE indexing in the forward kernel with the padded layout for consistency.
- Adding a new GTest suite (`test_fmha_bwd_kernel_padding.cpp`) with comprehensive tests for various padding scenarios, including zero-length
  sequences and deterministic mode.

* fix clang format

* Adapt fmha_bwd_runner.cpp to new q, kv sequence padding
Add backward q/kv sequence padding unit tests.

* [CK_TILE] fmha: Unify sequence length and padding handling

Refactor the handling of sequence lengths and padding in the
FMHA forward and backward kernels to provide a more unified and flexible
interface.

- Replaced `seqstart_padded_*_ptr` with a more robust system that uses
  `seqstart_*_ptr` for physical sequence lengths and introduces
  `seqlen_*_ptr` and `cu_seqlen_*_ptr` for logical (unpadded) lengths.
- Established a clear order of precedence for determining sequence
  length: cumulative lengths (`cu_seqlen_*_ptr`) take priority,
  followed by per-sequence lengths (`seqlen_*_ptr`), and finally
  physical lengths derived from `seqstart_*_ptr`.
- Clarified the distinction between "group mode" and "batch mode" and
  how sequence lengths are handled in each case.
- Renamed `cu_seqlen_kv_ptr` to `cu_seqlen_k_ptr` for consistency.
- Updated comments and documentation to reflect the new argument
  structure and usage.

---------

Co-authored-by: illsilin_amdeng <Illia.Silin@amd.com>
2025-10-29 13:56:11 +08:00
..

CK Tile Example Suite

This directory contains a comprehensive suite of examples demonstrating the CK Tile programming model for high-performance GPU kernels. Each example illustrates a key deep learning or HPC operation, implemented using tile-based parallelism, modular pipelines, and data movement policy.


What is CK Tile?

CK Tile is a composable GPU programming API that expresses kernels as a composition of "tiles"—rectangular blocks of computation and data movement. The pipeline & policy orchestrates data movement (global <-> LDS <-> registers), computation, and synchronization, enabling high efficiency and flexibility.


Example Index

Example Operation Description
01_fmha Fused Multi-Head Attention Tile-based FMHA with masking, quantization, and epilogue fusion
02_layernorm2d LayerNorm2D Blockwise layer normalization with fusion and quantization
03_gemm GEMM Matrix multiplication with tilewise parallelism
04_img2col im2col Image-to-column transformation for GEMM-based convolution
05_reduce Reduction Tilewise sum, max, mean reductions
06_permute Permute Generic tensor permutation (up to rank-8)
09_topk_softmax TopK-Softmax Rowwise softmax and top-k selection for MoE gating
10_rmsnorm2d RMSNorm2D Root mean square normalization for LLMs
11_add_rmsnorm2d_rdquant Add + RMSNorm2D + RDQuant Fused add, RMSNorm, and rowwise dynamic quantization
12_smoothquant SmoothQuant Per-channel scaling and quantization for int8 inference
13_moe_sorting MoE Sorting Token-to-expert rearrangement for MoE dispatch
14_moe_smoothquant MoE-SmoothQuant Expert-dependent quantization fused with top-k selection
15_fused_moe Fused MoE End-to-end fused MoE block: sorting, group-GEMM, activation, weighting
16_batched_gemm Batched GEMM Parallel computation of multiple GEMMs
17_grouped_gemm Grouped GEMM Multiple independent GEMMs with different shapes
18_flatmm FLATMM Flattened matrix multiplication for packed layouts
19_gemm_multi_d Multi-D GEMM GEMM with multiple side inputs (bias, residual, etc.)
35_batched_transpose Batched Transpose NCHW <-> NHWC and other layout conversions
36_copy Copy Minimal example for tile-based memory movement
37_transpose Block Transpose High-performance tiled transpose for large tensors

Technical Highlights


How to Build & Run

mkdir build && cd build
sh ../script/cmake-ck-dev.sh ../ <arch>
make -j

Each example produces its own executable in build/bin/.


Learning and Extending


References


Back to Composable Kernel Examples