Cooperative Data Sharing System (CDS)

Brief Description

CDS1 is a portable parallel communication library based on virtually-shared dynamic memory regions. (No special MMU support is required.) Communication is performed by passing virtualized pointers to these regions among processes through queue-like constructs called communication cells. As a result, both shared-memory and message-passing communication, as well as Linda-like production-consumption paradigms, are possible using a small set of simple primitives while still offering the user control over the placement and movement of data. The entire library of 26 functions also supports

multicast,
dynamic non-blocking process creation,
demand-driven communication (i.e. "get"),
asynchronous prefetch and data forwarding,
communication-driven execution (i.e. handlers), and
support for data translation for heterogeneous environments.

In spite of its simplicity, programs (using any or all of the primitives) are efficient in shared-memory, message-passing, and cluster environments, because:

As in shared memory models

Copying is not necessary for communication
Reading processes may share access to data (with copy-on-write to prevent race conditions)
Consuming processes can retrieve data from producing processes

As in message-passing models

Producing processes can forward data to consuming processes to compensate for latency in high-latency environments
Handlers can be installed to be invoked on the presence or absence of communicated data
Communicated data can be queued while awaiting processing

A prototype of the CDS1 interface has been implemented on SGI and Solaris clusters.

CDS1 is the lowest level of a larger system, called The Cooperative Data Sharing System (CDS). CDS is a means of programming parallel computers by describing how the data should be shared among the processors, rather than explicitly describing how the data should be communicated among the processors. This can yield more portable and correct programs, since the mechanics of communication can be handled automatically and can be performed using the most efficient mechanisms available for a particular architecture.

CDS2 is a higher-level subroutine layer, built upon CDS1, to provide a more complete interface for applications programmers at the cost of some additional overhead. CDS1 and CDS2 can be used together within the same user program. CDS2 is not yet complete.

More Information

Please Note: The papers listed are covered by the respective publisher's copyright. Although they can be viewed from this page for individual use, the rights of the publisher must be observed.

"A Simple and Efficient Process and Communication Abstraction for Network Operating Systems" , David C. DiNucci, Proceedings of the Workshop on Communication and Architectural Support for Network-Based Parallel Computing (CANPC) '97, San Antonio, Feb 1-2, 1997, published as LNCS volume 1199, pp. 31-45, D. Panda and C. Stunkel Eds.
- Slides (Postscript) Brief description of entire CDS1 package
"The Cooperative Data Sharing System, Level 1 (CDS1): A Reference Manual and User's Guide" , Working copy, unpublished, last updated 3/19/97.
- Paper (Postscript)
"Cooperative Data Sharing: A Layered Approach to an Architecture-Independent Message-Passing Interface", David C. DiNucci, Proceedings of the Second MPI Developer's Conference, Notre Dame, July 1996, IEEE, pp. 58-65.
- Paper (Postscript) CDS1 description slightly outdated, but includes brief description of CDS2.
- Slides (Postscript)
"Cooperative Data Sharing: An Architecture-Independent Interface for Implementing Parallel CFD Applications" , David C. DiNucci, HPCC Computational Aerosciences Workshop, August 1996, NASA Ames Research Center
- Extended Abstract (Postscript)
- Additional Slides (Postscript) Brief summary of meaning of "architecture-independence"
Brief Tutorial

Obtaining the Prototype

A prototype of the CDS1, which runs on SGI IRIX 5.3, IRIX 6.x, and (some) Sun Solaris platforms is currently available under the HPCC beta agreement. Until it is posted to the NAS Software Archive, requests should be sent to dinucci@nas.nasa.gov

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Updated: Tuesday, 03-Aug-1999 17:08:45 PDT
WebWork: Robert Hood
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