Modal Blog: Host Overhead Is Killing Your Inference Efficiency

Modal's blog explains how host overhead—gaps where the GPU sits idle waiting for the CPU to prepare work—shows up as low GPU kernel utilization in AI inference. At 50% host overhead, GPU inference costs are 2x what they could be. The post details fixes used in production open source inference engines, including constructing tensors on-device instead of transferring them and reducing unnecessary CUDA kernel launches.