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1f69421434
The shared-SRD buffer_load_dword_lds path that K_mem_load / V_mem_load use
wraps the per-lane voffset (int32 bytes) once
num_blocks * page_size * row_stride * sizeof(T) > INT32_MAX,
silently returning wrong data on large paged-KV pools (e.g. >4 GB caches).
Add a second path, async_load_tile_raw_long, that issues the same load via
__builtin_amdgcn_global_load_lds with per-lane 64-bit base pointers, lifting
both 4 GB limits (SRD size + voffset). Per-issue LDS pointers are computed
explicitly because the intrinsic sets m0 itself, so the old m0_set / m0_inc
bookkeeping doesn't apply. The path also clamps lane_elem_off to the live
buffer range to mimic the original SRD's hardware OOB behaviour.
Dispatch is a wave-uniform runtime branch on a new
cache_ptr_int32_overflow_possible flag plumbed from
unified_attention_args through MakeKargs into the pipeline operator().
Small caches keep the original buffer_load throughput; only the (rare)
>4 GB cache pays the global_load_lds cost.
k_page_offsets / v_page_offsets are widened to long_index_t. The original
buffer_load path implicitly narrows back to int32 when forwarding through
async_get_vectorized_elements_raw, which is intentional and safe whenever
the overflow flag is false.
For diagnostics, also derive a constexpr KWaveSpanInN =
(LaneGroups - 1) * NumWarps + 1 inside the pipeline; when this exceeds
page_size a single buffer_load spans multiple random pages, so the
per-issue SRD-rebase optimisation (not implemented yet) would not apply
even on a sub-4 GB cache. Informational only today.
Test: ua-test-scripts correctness sweep (245/245 pass), plus
test_single_shape.py -b 32 -sq 8192 -sk 120000 -hq 64 -hk 8 -d 64 \
--num-blocks 1200000 --block-size 16 --test
which previously returned wrong data due to the int32 wrap and now passes
with max abs diff 1.22e-04 vs Triton.
Co-authored-by: Cursor <cursoragent@cursor.com>
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
- Tile Distribution: See
include/ck_tile/tile_program/tile_distribution/for mapping tiles to thread blocks. - Block Tile Pipelines: See
include/ck_tile/tile_program/block_tile_pipeline/for memory/computation pipelines. - Policies and Utilities: Many examples use custom policies for tile/block size and memory access.
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
- Start Simple: Try 03_gemm or 36_copy to learn tile basics.
- Explore Fusion: See 11_add_rmsnorm2d_rdquant, 15_fused_moe, or 14_moe_smoothquant for advanced fusion.
- Experiment: Modify tile sizes, layouts, or pipelines to explore performance and flexibility.