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Inria / Raweb 2003
Project: PARIS

Project : paris

Section: Software


Keywords : DSM , data repository .

Mome

Participant : Yvon Jégou.

Contact:

Yvon Jégou

Status:

Prototype under development

Contact:

Yvon Jégou, http://www.irisa.fr/paris/Mome/welcome.htm

License:

APP registration in the future, license type not yet defined (LGPL?).

Presentation:

The Mome DSM provides a shared segment space to parallel programs running on distributed memory computers or clusters. Individual processes can freely request mappings between their local address space and Mome segments. The DSM handles the consistency of mapped memory regions at the page-level. Two consistency models are currently implemented and can be selected by the user programs at the page level: the classical sequential model and an explicit weak model. Mome initial target was the execution of programs from the high performance community which exploit loop-level parallelism using a Spmd computation model. the current release of Mome supports

  • page aliasing: the same page can be mapped twice (or more) in the same address space. This feature is used in the implementation of a DSM-based coupling library.

  • heterogeneous applications: different programs (binaries) can share data (be coupled) through the same instance of the DSM.

  • checkpointing: on checkpointing request from the application, the DSM guarantees that two copies of each DSM page are present on two different nodes. In case of failure, it is possible to restart the DSM and to recover all the pages of the last checkpoint as long as one node maximum that participated to the checkpoint has crashed.

  • dynamic connection of processes: Mome can be started as a background daemon and supports the dynamic connection of processes. This possibility allows the implementation of persistent data repositories.

The current developments around Mome involve the implementation of an OpenMP runtime system, the implementation of a DSM-based coupling library and the development of a persistent data repository for the grid.

Current status:

Mome is implemented in C (50,000 lines) and represents a 24-person-month effort. The current release is Mome  0.8. The DSM is used in Alcatel collaboration (checkpointing), in VTHD contracts (code coupling using a DSM), in e-Toile project (DSM-based data-repository for grid computing) and in the POP project (OpenMP runtime).


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