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[CK Tile] StreamK support for Bwd Weight grouped convolutions (#5393) ## Motivation Add StreamK work distribution to the CK Tile grouped convolution backward weight kernel. Split-K divides the K-dimension uniformly across a fixed `k_batch`, which causes load imbalance when the number of output tiles doesn't evenly fill the GPU. StreamK distributes total K-iterations evenly across workgroups, improving utilization on these shapes. ## Technical Details StreamK is added as an `if constexpr` branch in the existing kernel, selected by the `TilePartitioner_` template parameter. Two reduction strategies are supported: - **Linear**: tile-starter sequentially accumulates partials from contributing CTAs - **Tree**: pairwise binary tree reduction (O(log n) depth, faster for many contributors) Both persistent and non-persistent data-parallel (DP) sections are supported. Key changes: - `grouped_convolution_backward_weight_kernel.hpp`: StreamK execution path with `RunStreamK`/`RunStreamKLoop`, partial store/load via workspace, flag-based cross-CTA synchronization, `GridSize`/`MakeKernelArgs`/`GetWorkSpaceSize` extensions - `streamk_common.hpp`: Shared `StreamKReductionOps` (reduction helpers) and `StreamKDispatch` (persistent/non-persistent DP dispatch), used by both GEMM and Conv StreamK kernels - `streamk_gemm_kernel.hpp`: Refactored to use shared helpers - Merged split-K and StreamK example invokers via `PartitionerPolicy` template parameter - StreamK example binary with `--streamk_reduction=linear|tree` and `--streamk_persistent=0|1` - CK Builder integration: `SpecifiesStreamK` concept, `TilePartitionerType` factory helper, `InstanceTraits` with StreamK fields - 30 tests: host-side, GPU end-to-end (Linear + Tree + Persistent DP), negative, builder regression ### Performance (MI355X, gfx950) Speedup relative to best split-K (sweep over k_batch={1,2,4,8,16,32}): | Shape | 16x64 tiles | | 128x128 tiles | | |---|---|---|---|---| | | Split-K | StreamK | Split-K | StreamK | | 1x1 128x128 N=32 28x28 | 1.00x | 0.54x | 1.00x | 0.81x | | 3x3 128x128 N=32 14x14 | 1.00x | 0.59x | 1.00x | 0.62x | | 1x1 256x64 N=32 56x56 | 1.00x | 0.83x | 1.00x | 1.83x | | 3x3 512x512 N=2 7x7 | 1.00x | 1.12x | 1.00x | 0.62x | | 1x1 1024x1024 N=4 7x7 | 1.00x | 1.09x | 1.00x | 0.60x | | 3x3 128x128 N=32 28x28 | 1.00x | 0.44x | 1.00x | 0.96x | | 3x3 256x256 N=32 14x14 | 1.00x | 0.67x | 1.00x | 0.93x | | 3x3 512x512 N=32 7x7 | 1.00x | 0.98x | 1.00x | 1.16x | StreamK's value depends on tile config: with larger tiles (fewer output tiles), StreamK delivers up to 1.83x speedup on bottleneck shapes and up to 1.16x on typical large-channel convolutions. Tree reduction consistently outperforms Linear when multiple CTAs contribute to the same tile (up to 2.87x faster), due to O(log n) reduction depth vs O(n) sequential accumulation. The table reports the best of Linear and Tree for each shape. ## Test Plan ```bash ninja -C build test_ck_tile_grouped_conv_bwd_weight_streamk ./build/bin/test_ck_tile_grouped_conv_bwd_weight_streamk # Builder tests (requires CK_EXPERIMENTAL_BUILDER=ON) ninja -C build check-builder ``` 30 tests covering: - Host-side: type traits, kernel args construction, grid size, workspace size - GPU end-to-end (Linear + Tree): small/medium shapes, multi-group, stride>1, pure-DP degeneration, single-tile all-SK, large GemmK, higher occupancy - Persistent DP: Linear + Tree with persistent data-parallel dispatch - Negative: `IsSupportedArgument` rejects unaligned K and C - Builder: Create (instance string validation) + Execution (reference comparison) + instance string regression ## Test Result All 30 conv StreamK tests pass on MI355X (gfx950). 64/64 GEMM StreamK tests pass. Full `check-builder` suite passes. Tolerances computed dynamically using `calculate_rtol_atol` pattern (fp16 ULP-aware). ## Submission Checklist - [x] Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.
Composable Kernel Tile
concept
ck_tile provides a programming model with templated abstractions to enable users to implement performance-critical kernels for machine learning workloads. introduces following basic concepts to help users building your own operator
- tensor coordinate transformation, this is the core concept of layout/index transform abstraction in both compiler time and run time.
- tile-based programming model, including tile-level api and the concept of distributed tensor.
ck_tile is independently from the old ck, located under /include/ck_tile. You don't need to include anything from old CK, ck_tile has similiar (indeed almost the same) implementations for users to build operators. We will have a transition period to pull everything from old ck into ck_tile, stay tuned.
component
ck_tile is splitted into several componenets including core, host, ops/gemm, ops/fmha... each component you only need to include a single header (e.g #include "ck_tile/core.hpp", #include "ck_tile/ops/fmha.hpp") then you are able to use the function/structure inside (different from old ck)
[core]
ck_tile/core contains all the basic data structure and function to build the kernel, you can only include this header and build your own operators that utilizing all the basic building blocks introduced in ck.
core/container
- array, store runtime variables with fixed length (tensor index, register buffer, etc...)
- tuple, same as std::tuple, hold different type of data, and one of the solution to achieve multiple buffer.
- sequence, compile time integer sequence used to build various internal structures, or to describe tile size
- other convenient structure build on top of above 3
core/numeric
- gpu data type like
fp16_t,bf16_t,fp8_t... and the conversion between each other - constexpr integer similiar to std::integral_constant to be used as compile time integer.
- math functions and numeric utilities
core/algorithm
- coordinate transformation system, used to build tensor transform and compile time indexing. This is the core idea introduced in old
ckto describe how a tensor is build by several basic transform primitives likemerge/unmerge/embedetc... and how we indexing into a ND tensor that finally mapped to 1D memory offset.
core/tensor
- tensor descriptor, to describe how a ND tensor
- distributed tensor, describe the storage of this tensor, and the distribution of how a collection of threads collaborately work for this tensor.
- tile level API, including
load_tile,store_tile,shuffle_tile,slice_tile, etc...
[host]
ck_tile/host contains all the host side utilities to launch a kernel, create the device buffer, and some reference implementations. This can be used to create examples (like that under ck_tile example folder) and simple executable to invoke this kernel, so if you only need ck_tile to build your own device library then it's OK to not include this. Based on this, it is recommended to include the specific header you needed under this folder to avoid including unwanted headers (e.g, only include ck_tile/host/kernel_launch.hpp), unless you are writing a host executable.
[ops/gemm, ops/fmha, ops/reduce...]
our implementation of different device operators.
- warp, warp tile level operator
- block, block tile level operator
- pipeline, pipeline that can achieve a customized tile level mainloop (or epilogue). By switching different pipeline to the kernel template you can have different kind of pipeline optimizations.
- kernel, template interface for users to instantiate a particular kernel
[ops/epilogue]
epilogue part of our kernel. We may extend this epilogue part to let users to build their own cutomized epilogues.
[ref]
reference implementation of cpu or gpu. This folder is supposed to include a specific header on demand.
examples
currently we put all ck_tile related example under /example/ck_tile folder. Please check each example's subfolder.