vMPI

vmpi, short for Virtual Message Passing Interface, is a term used to describe MPI-compatible software layers that enable running MPI applications in nontraditional environments—such as virtual machines, containers, or cloud infrastructure—where a native MPI stack is difficult to deploy. The term does not refer to a single standard; instead it encompasses several independent projects and research prototypes that implement the MPI API over alternative transport mechanisms.

Typical aims are portability, rapid deployment, and the ability to run MPI programs without administrative privileges. Implementations usually expose the MPI API (including point-to-point and collective operations) while decoupling the API from the underlying transport.

Under the hood, vMPI runtimes may use shared memory for intranode communication, and user-space networking or overlay protocols for internode communication. Some projects rely on virtual networks or cloud networking primitives; performance can be sensitive to virtualization overhead and network configuration.

Limitations include potential compatibility gaps with vendor-specific MPI features, reduced performance compared with native MPI stacks, and ongoing maintenance needs. Use cases include education, experimentation, and running MPI workloads in lab or cloud environments where traditional MPI deployments are impractical.

In practice, vMPI is a niche solution rather than a standard component of HPC stacks. For most production workloads, established MPI implementations such as Open MPI or MPICH are preferred, while vMPI variants serve as tools for testing, portability, and research into runtime systems for MPI in virtualized contexts.