Filter placement on a pipelined architecture

In this paper, we explore the problem of mapping filtering query services on chains of heterogeneous processors. Two important optimization criteria should be considered in such a framework. The period, which is the inverse of the throughput, measures the rate at which data sets can enter the system. The latency measures the response time of the system in order to process one single data set entirely. We provide a comprehensive set of complexity results for period and latency optimization problems, with proportional or arbitrary computation costs, and without or with communication costs. We present polynomial algorithms for problems whose dependence graph is a linear chain (hence a fixed ordering of the filtering services). For independent services, the problems are all NP-complete except latency minimization with proportional computation costs, which was shown polynomial in [6].