Posts by Clement Lin
Avoiding LDS Bank Conflicts on AMD GPUs Using CK-Tile Framework
- 25 July 2025
LDS bank conflict is a common performance bottleneck in GPU kernel development. Composable Kernel (CK-Tile), a kernel development framework for AMD GPUs, provides a framework-level solution for LDS bank conflicts. Composable Kernel for ROCm is used to build portable high-performance kernels for accelerating computing, e.g. HPC, DL and LLMs for training and inference workloads. In this blog, we show you how to analyze, detect, and eliminate LDS bank conflicts using CK-Tile, AMD’s composable GPU kernel framework. A GEMM kernel serves as a classic example for analyzing how threads interact with LDS during both reads and writes. Starting with a naïve memory layout, we evaluate bank conflict behavior, explore mitigation techniques such as padding, and ultimately demonstrate how an XOR-based swizzle transformation achieves a bank conflict-free design.