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CUDA HGEMM

Several optimization methods of half-precision general matrix multiplication (HGEMM) using tensor core with WMMA API and MMA PTX instruction. The calculation expression is as follows, where the precision of matrix A (M * K), B (K * N) and C (M * N) is FP16. Through exploring various matrix tiling and optimization methods, the current performance between 256 to 16384 dimensions is not less than 95% of the performance of cublas, and in many scenarios, it exceeds the performance of cublas.

C (M * N) = A (M * K) * B (K * N)

hgemm

Optimization Method

Tiling: 256 * 128 for block tiling size and 64 * 64 for warp tiling size
Coalescing Access: using wide instruction access to global memory
Data Reuse: using shared memory to reuse data of matrix A and B
Async Copy: using asynchronous copy operation with non-blocking instruction
Bank Conflict: using padding method for WMMA API and permuted method for MMA PTX instruction to eliminate bank conflict
L2 Cache: using swizzle access mode to increase L2 cache hit ratio
Register Reuse: calculating as "Right Left Right Left" for the internal tile of warp
Pg2s: double-buffer algorithm using prefetching global memory to shared memory
Ps2r: double-buffer algorithm using prefetching shared memory to register
Stage: multi-buffer algorithm using prefetching global memory to shared memory

Compile

Environment

OS: Linux
Cmake Version: >= 3.12
GCC Version: >= 4.8
CUDA Version: >= 11.0
Others: gflags, ccache

sudo apt-get install libgflags-dev ccache

Clone

git clone https://github.com/Bruce-Lee-LY/cuda_hgemm.git

Build

NVIDIA A100

cd cuda_hgemm
./build.sh -a 80 -t Release -b OFF
./build.sh -a 80 -t Debug -b OFF

RTX3080Ti / RTX3090 / RTX A6000

cd cuda_hgemm
./build.sh -a 86 -t Release -b OFF
./build.sh -a 86 -t Debug -b OFF

Run Sample

./run_sample.sh

Performance

Process the data in the log and plot it as a line chart.

cd tools/performance
./performance.sh

RTX3090

CUDA Version: 11.3

The best performance that can be achieved.

best_throughput

Performance achieved by current optimization methods.

throughput

RTX A6000

CUDA Version: 11.3

The best performance that can be achieved.

best_throughput