Development of a network supercomputing environment with fine grain dynamic load distribution mechanism

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1. Load Balancing MechanismA fundamental protocol for work migration was developed. In this protocol, exactly the minimum amount of private information, like a stack, necessary to resume execution at the destination node is migrated, so that it could reduce the time until the work resumes execution. The rest of information is declared as temporary shared region between source and destination nodes of the migration and is kept not transferred until it is accessed. When it is accessed, a small amount of data close to the accessed address is transferred as a cached copy of shared data.Then, we proposed the implementation that the work migration mechanism maintains some amount of memory space for its own use and it immediately assigns only a constant amount of area out of this space to the immigrant without any negotiation with a memory management mechanism.In addition, we proposed the difference transportation method to reduce needless data transfer. When the work migration happens between two nodes in back and forth fashion, by using the past history, this method extracts the difference of the contexts between two nodes and applies a patch using the difference.2. Computer Colony Experimental EnvironmentAs a prototype environment, a simple shared memory environment where two workstations eauipped with SPARC version LINUX were connected by the originally developed network interface cards which efficiently support shared virtual memory. In order to realize user-level access to this card, we have modified the Linux kernel briefly.The result of the evaluation of the speed of a fine grain local shared memory access said that the user-level access is about eight times faster than the access through system call. It is also found that the average latency of remote memory access became 2.7 and 2.3 microseconds for Read and Write accesses respectively.