Formal specification of MPI 2.0: Case study in specifying a practical concurrent programming API

Abstract

a b s t r a c tWe describe the first formal specification of a non-trivial subset of MPI, the dominant communication API in high performance computing. Engineering a formal specification for a non-trivial concurrency API requires the right combination of rigor, executability, and traceability, while also serving as a smooth elaboration of a pre-existing informal specification. It also requires the modularization of reusable specification components to keep the length of the specification in check. Long-lived APIs such as MPI are not usually 'textbook minimalistic' because they support a diverse array of applications, a diverse community of users, and have efficient implementations over decades of computing hardware. We choose the TLA+ notation to write our specifications, and describe how we organized the specification of around 200 of the 300 MPI 2.0 functions. We detail a handful of these functions in this paper, and assess our specification with respect to the aforementioned requirements. We close with a description of possible approaches that may help render the act of writing, understanding, and validating the specifications of concurrency APIs much more productive.

Scalable SMT-based verification of GPU kernel functions

“…The main challenge, however, is to model involved APIs and system calls. One solution is to build light-weight models or abstract interpretations for these APIs as we did for MPI 2.0 [18].…”

Formal Analysis of Message Passing

“…Instead, this decision is a natural consequence of exploiting the happens-before order we have defined for MPI [47]. While MPI itself can be formalized in several ways (e.g., [35,22]), we have found that it is this more "macroscopic" formal semantics of happens-before ordering that directly guides the construction of the ISP scheduler.…”