jinmin527 / cuda_hgemm

Several optimization methods of half-precision general matrix multiplication (HGEMM) using tensor core with WMMA API and MMA PTX instruction.

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)

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
• Gflags: install on ubuntu as follows

sudo apt-get install libgflags-dev

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.

Performance achieved by current optimization methods.

RTX A6000

• CUDA Version: 11.3

The best performance that can be achieved.