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* Wrap ck host utitlies in CK namespace.
The CK and CK-Tile source code bases are incompatible because CK is not properly using namespaces everywhere. In particular, we need to put hip_check_error in the ck namespace.
Move all functions in include/ck_/host_utility that were in global namespace into the ck namespace.
There may be additional namespace problems like this, and it's possible we'll have namespace clashes. But it is good design to properly guard our to code bases (CK and CKTile) so that they can both coexist. Moreover, estabilishing this compatiblity is essential if we are going to allow the builder to instantiate kernels from either template library.
* Add using declarations to test code.
After moving some of the untils into the ck namespace, most examples and a few tests had to be updated to recognize the new namespace declarations. We add using declarations to individual compute units for functions that were previously in the global namespace.
* Add using declarations to client examples.
[ROCm/composable_kernel commit: ad57f6ef0b]
Batched GEMM
Theory
This example demonstrates batched GEMM: performing multiple independent matrix multiplications (all with the same shape) in a single kernel launch. Batched GEMM is used in multi-head attention, RNNs, and other models requiring parallel matrix multiplications.
Mathematical Formulation:
For B batches:
C_b = A_b \times B_b \quad \text{for} \quad b = 1, 2, ..., B
A_b: [M, K] input matrix for batchbB_b: [K, N] weight matrix for batchbC_b: [M, N] output matrix for batchb
Algorithmic Background:
- All matrices in the batch have the same shape and strides.
- The kernel launches a grid covering all batches, with each block assigned to a batch.
- Used for multi-head attention, parallel MLPs, and more.
How to Run
Prerequisites
Please follow the instructions in the main Build Guide section as a prerequisite to building and running this example.
Build and run
cd composable_kernel/example/24_batched_gemm
mkdir build && cd build
cmake -DCMAKE_CXX_COMPILER=/opt/rocm/bin/hipcc ..
make -j
# Example run
./batched_gemm_xdl --verify=1 --time=1
Source Code Structure
Directory Layout
example/24_batched_gemm/
├── batched_gemm_xdl.cpp # Main example: sets up, runs, and verifies batched GEMM
include/ck/tensor_operation/gpu/device/
│ └── device_batched_gemm_xdl.hpp # Device-level batched GEMM API
include/ck/tensor_operation/gpu/grid/
│ └── gridwise_batched_gemm_xdl.hpp # Grid-level batched GEMM kernel
Key Classes and Functions
- DeviceBatchedGemmXdl (in
device_batched_gemm_xdl.hpp):
Device API for batched GEMM. - gridwise_batched_gemm_xdl (in
gridwise_batched_gemm_xdl.hpp):
Implements the tiled/blocking batched GEMM kernel.
This example demonstrates how Composable Kernel supports efficient parallel matrix multiplication for batched and multi-head workloads.