When developing an application from scratch it is feasible to design the code, data structures, and data movement to support accelerators. However when facing an existing application it is often hard to know where to start, what to expect, and how best to make use of an accelerator like a GPU. Based on our experience working with various application developers to help them accelerate applications using NVIDIA GPUs, we have documented a process that allows one to incrementally add improvements to the code. It’s not complex, and to some people it may be obvious, but even for experts writing it down helps to structure the effort and leads to faster results.
The process consists of four stages: Assess, Parallelize, Optimize, Deploy, or APOD, executed in a cycle. Having identified where to start developing, our goal is to realize and deploy a benefit before returning to the first stage, Assess, and adding further improvements.