Multicast decomposition mechanism in a hierarchically order distributed shared memory multiprocessor computer system

• US 20020009095A1
• Filed: 05/31/2001
• Published: 01/24/2002
• Est. Priority Date: 05/31/2000
• Status: Abandoned Application

• Current Assignee: Compaq Computer Corporation (HP Inc.)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Steely, Simon C. Jr., Van Doren, Stephen R., Sharma, Madhumitra
• Application Number:
  US09/871,054
• Publication Number:
  US 20020009095A1
• Time in Patent Office: Days
• US Class Current: 370/432
• CPC Class Codes: G06F 15/17393 having multistage networks, e.g. broadcasting scattering, gathering, hot spot contention, combining/decombining
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/16 Multipoint routing

Abstract

A technique decomposes a multicast transaction issued by one of a plurality of nodes of a distributed shared memory multiprocessor system into a series of multicast packets, each of which may further “spawn” multicast messages directed to a subset of the nodes. A central switch fabric interconnects the nodes, each of which includes a global port coupled to the switch, a plurality of processors and memory. The central switch includes a central ordering point that maintains an order of packets issued by, e.g., a source processor of a remote node when requesting data resident in a memory of a home node. The multicast messages spawned from a multicast packet passing the central ordering point are generated according to multicast decomposition and ordering rules of the inventive technique.

Claims

1. A method for decomposing a multicast transaction into multicast messages directed to targeted nodes of a distributed shared memory multiprocessor system, the multicast transaction issued by a source node of the system to acquire data stored on a home node of the system, the method comprising the steps of:

apportioning the multicast transaction into a predetermined number of multicast packets at a global port of the home node;

forwarding the multicast packets to a central switch fabric interconnecting nodes;

generating the multicast messages from the packets at the central switch fabric, the multicast messages generated according to multicast decomposition and ordering rules; and

distributing the multicast messages to the targeted nodes.

2. The method of claim 1 wherein:

the multicast messages include a commit signal (comsig) and one or more comsig supporting messages, and

the comsig and the one or more comsig supporting messages are distributed last.

4. The method of claim 1 wherein the multicast message associated with the source node is a command response message and wherein the multicast message associated with the home node is a comsig supporting message.

3. The method of claim I wherein the step of generating the multicast messages comprises the step of generating the multicast messages associated with the source node and the home node as a result of the last packet in the predetermined number of multicast packets.