Performance of an OLTP application on symmetry multiprocessor system

Sequent's Symmetry Series is a bus-based shared-memory multiprocessor. System performance in an OLTP relational database application was investigated using the TP1 benchmark. System performance was tested with fully-cached benchmarks and with scaled benchmarks. In fully-cached tests, the entire database fits inside main memory. In scaled tests, the database is larger than available memory. In the fully-cached benchmark, performance was initially limited by bus saturation. The cause was the transfer of process context from processor to processor. This was eliminated by assigning each process to a processor. Processor affinity was combined with reductions in message-passing within the database. Throughput was dramatically improved. The scaled tests were I/O bound. This bottleneck can be eliminated by connecting more disk drives, or by increasing the main memory size.