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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.
GEMM with LayerNorm Fusion
Theory
This example demonstrates GEMM fused with layer normalization. This pattern is used in transformer feed-forward networks and other architectures where a linear transformation is followed by normalization for improved training stability.
Mathematical Formulation:
- GEMM:
Y = A \times B - LayerNorm:
\text{LayerNorm}(Y) = \gamma \cdot \frac{Y - \mu}{\sqrt{\sigma^2 + \epsilon}} + \beta\mu: mean ofYover the normalization axis\sigma^2: variance ofYover the normalization axis\gamma,\beta: learnable scale and shift parameters
Algorithmic Background:
- The GEMM result is kept in registers, and layer normalization is applied before writing to global memory.
- LayerNorm is typically applied over the last dimension (features).
- This fusion reduces memory traffic and is common in transformer MLP blocks.
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/21_gemm_layernorm
mkdir build && cd build
cmake -DCMAKE_CXX_COMPILER=/opt/rocm/bin/hipcc ..
make -j
# Example run
./gemm_layernorm_xdl --verify=1 --time=1
Source Code Structure
Directory Layout
example/21_gemm_layernorm/
├── gemm_layernorm_xdl.cpp # Main example: sets up, runs, and verifies GEMM+LayerNorm
include/ck/tensor_operation/gpu/device/
│ └── device_gemm_layernorm.hpp # Device-level GEMM+LayerNorm API
include/ck/tensor_operation/gpu/device/impl/
│ └── device_gemm_layernorm_impl.hpp # Implementation
include/ck/tensor_operation/gpu/grid/
└── gridwise_gemm_layernorm.hpp # Grid-level kernel
Key Classes and Functions
- DeviceGemmLayerNorm (in
device_gemm_layernorm.hpp):
Device API for GEMM fused with layer normalization. - gridwise_gemm_layernorm (in
gridwise_gemm_layernorm.hpp):
Implements the tiled/blocking GEMM kernel with layer normalization epilogue.
This example demonstrates how Composable Kernel supports efficient fusion of linear and normalization layers for transformer and deep learning models.