SYSTEM AND METHOD FOR DETERMINING GLOBAL VIRTUAL TIME IN OPTIMISTIC PARALLEL DISCRETE EVENT SIMULATIONS

摘要

A system (100) and method for determining Global Virtual Time (GVT) is provided. The system (100) comprises a plurality of nodes (101, 102) of parallel processors including at least one requesting node (102) for generating a GVT update request and a plurality of responding nodes (102) for generating respective responses to the GVT update request. At least one intermediate node (101) is coupled to the requesting node (102) and to the responding nodes (102) such that respective responses are passed through the intermediate node (101). The intermediate node (101) includes a memory (203) configured to store therein information obtained from the response packets, the information including the LVTs of response packets. According to the method of the invention at least one GVT update request is sent by a requesting node. A plurality of responding nodes generate respective response packets directed to the requesting node. Each of the respective response packets includes the LVT of a corresponding responding node. As response packets pass through one or more intermediate nodes, the LVT of each response packet is compared with an LVT stored in a memory of the intermediate node to determine which LVT is earlier in time. If the LVT of the response packet is earlier in time than an LVT stored in a memory of the intermediate node, the response packet is routed through the intermediate device unchanged. If the LVT of the response packet is not earlier in time than the LVT in a memory of the intermediate device, the response packet is either updated or dropped, depending on whether the response packet is the first to pass through the intermediate device. The requesting node compares the LVTs of all responses it receives to determine which is earliest in time.