Accelerating DSS Workloads through Coherence Protocols
Pierfrancesco Foglia, Cosimo Antonio Prete, Roberto Giorgi · 2001
In this work, we analyze how a DSS (Decision Support System) workload can be accelerated in the case of a shared-bus shared-memory multiprocessor, by adding simple support to the classical MESI solution for the coherence protocol. The DSS workload has been set-up utilizing the TPC-D benchmark on the PostgreSQL DBMS. Analysis has been performed via trace driven simulation and the operating system effects are also considered in our evaluation. We analyzed a basic four-processor and a high-end sixteen-processor machine, implementing MESI and two coherence protocols which deal with migration of processes and data: PSCR and AMSD. Results show that, even in the four processor case, PSCR outperforms the other protocol, because of the lower bus utilization due to the absence of invalidation miss when we eliminate the contribution of passive sharing. In the 16 processor case, with bus near to saturation, the gain of PSCR becomes more important and the advantage of PSCR could be quantified in a 10 % relatively to the other evaluated protocol. Keywords: Shared-Bus Multiprocessors, DSS system,