An Example of Porting PETSc Applications to Heterogeneous Platforms with OpenACC

In this paper, we document the workflow of our practice to port a PETSc application with OpenACC to a supercomputer, Titan, at Oak Ridge National Laboratory. Our experience shows a few lines of code modifications with OpenACC directives can give us a speedup of 1.34x in a PETSc-based Poisson solver (conjugate gradient method with algebraic multigrid preconditioner). This demonstrates the feasibility of enabling GPU capability in PETSc with OpenACC. We hope our work can serve as a reference to those who are interested in porting their legacy PETSc applications to modern heterogeneous platforms.