
Frozen layer memory footprint. During training, AutoPipe must recompute partition boundaries several times to balance two distinct types of layers: frozen layers and active layers. The frozen layer's memory cost is a fraction of that inactive layer, given that the frozen layer does not need backward activation maps, optimizer states, and gradients. Instead of launching intrusive profilers to obtain thorough metrics on memory and computational cost, we define a tunable cost factor  to estimate the memory footprint ratio of a frozen layer over the same active layer. Based on empirical measurements in our experimental hardware, we set it to .




