NCSA Releases VMI 2.1
CHAMPAIGN, IL, Mar 24, 2005--The National Center for Supercomputing Applications (NCSA) is pleased to announce the release of version 2.1 of its Virtual Machine Interface (VMI) software.
        VMI is a middleware communication layer that addresses the issues of availability, usability, and management in the context of large-scale SANs interconnected over wide-area computational grids. With VMI, users are able to run applications on distributed clusters that use different types of interconnects to communicate among processors.
        The current release supports AMD Opterons, Intel X86-64, IA32, IA64 and PowerPC platforms running the Linux operating system. This release supports spanning a single MPI job across geographically distributed clusters. With the ability to load multiple communication devices at runtime, a high performance SAN network can be used for intra cluster communication while using TCP for inter cluster communication transparently.
        An MPI communication profiling framework is included for characterizing runtime communication parameters on an individual job basis to a database for subsequent analysis. MPICH-VMI supports profile guided optimization (PGO) at runtime for cross cluster communication by using the profile database. Communication characteristics from previous runs are used to optimize the mapping of virtual MPI ranks to physical processors to minimize the utilization of high latency low bandwidth links present in wide are grids.
        Significant scaleability related features have been added that improve startup times for large processor counts with considerably less resource usage requirements. MPI applications been successfully tested upto 1024 processors using Infiniband and 2500 processors running Myrinet. Enhanced features for asynchronous communication have been added with this release to provide increased capability to overlap communication and computation. The RDMA API supported by VMI has been expanded to include support for RDMA Gets. VMI will transparently emulate RDMA Get semantics in an efficient manner on hardware that does not support it or leverage hardware assisted RDMA Gets on networks that do provide the capability .

Features of VMI 2.1 include:

  • Support for AMD Opterons, Intel X86-64, IA-64, IA-32 and PowerPC platforms running the Linux operating system.
  • Support for multiple communication interconnects, including Shared Memory for intra node communication, TCP/IP, Myricom's Myrinet GM, Infiniband using VAPI, OpenIB and IBAL interfaces and iWarp using CCIL from Ammasso.
  • MPI support for grid based computing with multiple communication networks active concurrently.
  • Improved bandwidth and latency response across all communication networks. MPI latencies of 3.75 usec and peak bandwidth of 980 MB/sec have been achieved with Infiniband on PCI-Express.
  • Comprehensive support for RDMA communications. Supports both RDMA Get and Put semantics.
  • Designed for extremely large clusters with minimal demand for resources.
  • A profiling interface for profile guided optimization (PGO) for large grid runs spanning high latency low bandwidth networks.
  • An experimental implementation of MPI collectives utilizing hardware level multicast. Currently MPI Broadcast utilizes multicast communication primitives.
  • Support for the industry standard Message Passing Interface (MPI) parallel computing API, enabling many existing codes to run in a cluster environment simply by recompiling. MPI support is based on MPICH version 1.2.5 from Argonne National Laboratory.
  • Binary portability of MPI applications across interconnects without requiring recompilation of application software.

        Source code is available under a liberal open source-style license that allows redistribution in source or binary form provided that copyright notices and disclaimers remain intact. The release is available for download from the VMI project website (http://vmi.ncsa.uiuc.edu/). Access to documentation, a bug reporting tool, and support mail lists are also available at the site.


NCSA (National Center for Supercomputing Applications) is a national high-performance computing center that develops and deploys cutting-edge computing, networking and information technologies. Located at the University of Illinois at Urbana-Champaign, NCSA is funded by the National Science Foundation. Additional support comes from the state of Illinois, the University of Illinois, private sector partners and other federal agencies. For more information, see http://www.ncsa.uiuc.edu/.