Characterizing CNN Throughput and Energy Under Multithreaded and Multiaccelerator Execution

Emerging applications and batch processing convolutional neural network (CNN) workloads require executing multiple CNNs concurrently. A wide variety of CNN accelerators are available today and we characterize the support for concurrency for CNNs in such accelerators. We use a commercial-off-the-shelf CNN accelerator in multithreading and multiaccelerator modes and identify that upto $3.98\times $ improvement in throughput and $3.20\times $ improvement in energy per inference can be obtained even with just a single accelerator. Our detailed characterization of 104 CNN models, for three different sizes of accelerator, reveals many insights that connect CNN characteristics to improvement in throughput and energy. We also present a design space and a low error throughput estimation model to explore such a design space.