Direct Cache Access for High Bandwidth Network I/O

Abstract

Recent I/O technologies such as PCI-Express and 10Gb Ethernet enable unprecedented levels of I/O bandwidths in mainstream platforms. However, in traditional architectures, memory latency alone can limit processors from matching 10 Gb inbound network I/O traffic. We propose a platform-wide method called Direct Cache Access (DCA) to deliver inbound I/O data directly into processor caches. We demonstrate that DCA provides a significant reduction in memory latency and memory bandwidth for receive intensive network I/O applications. Analysis of benchmarks such as SPECWeb9, TPC-W and TPC-C shows that overall benefit depends on the relative volume of I/O to memory traffic as well as the spatial and temporal relationship between processor and I/O memory accesses. A system level perspective for the efficient implementation of DCA is presented.