Implementation and experimental performance evaluation of a hybrid interrupt-handling scheme

Abstract

The heavy traffic introduced by Gigabit networks can result in a significant degradation in the performance of network hosts. This degradation happens as a result of the interrupt overhead associated with the high rate of packet arrival. NAPI, the latest version of Linux networking subsystem, was designed to improve Linux performance to suit today's Gigabit traffic. NAPI is definitely a major step up from earlier Linux versions. However, NAPI has shortcomings and its performance can be enhanced considerably. A hybrid interrupt-handling scheme that switches between interrupt disabling-enabling and the polling can improve the performance of Gigabit network hosts in terms of throughput, latency, and CPU availability. In this research work, we modify and instrument the latest version of Linux kernel 2.6.15 to implement efficiently the hybrid scheme. We prove experimentally that the hybrid scheme outperforms NAPI under specific system configurations and load conditions.