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Abstract : |
Abstract: This paper presents a new approach to implement global reduction operations (including barrier synchronization) in wormhole k-ary n-cubes. The novelty lies in using multidestination message passing mechanism instead of single destination (unicast) messages. Using pairwise exchange worms along each dimension, it is shown that global reduction and barrier synchronization operations, as defined by the Message Passing Interface (MPI) standard, can be implemented with n communication start-ups as compared to 2ndlog 2 ke start-ups required with unicast-based message passing. This leads to an asymptotic improvement by a factor of d2log 2 ke. For different values of communication start-up time and system size, the analysis indicates that the new framework can implement fast global reduction compared to the unicast-based scheme. Issues related to the new approach are studied and the required architectural modifications to the router interface are presented. The analysis indicates that as the communication start-up time continues to decrease in new generation systems, the proposed framework can be used for implementing fast global reduction and barrier synchronization in, |
