Attention

Background Frequent HBM Access Creates an I/O Bottleneck in Standard Attention The authors focus on the I/O bottleneck in attention, pointing to the frequent HBM accesses in standard implementations as a major cause. To understand what is going on, we first need to look at the memory hierarchy found in GPUs and most other accelerators. Improving Actual Wall-Clock Time, Not Just Reducing FLOPs The authors note that previous work has tried to reduce the compute and memory complexity of attention, but many of those studies do not report improvements in actual wall-clock time. Their explanation is that these approaches tend to focus on reducing theoretical operation counts while overlooking the overhead of memory access. ...