Integrated performance evaluating criterion for selecting between interrupt coalescing and normal interruption

Abstract

Interrupt coalescing is a feature implemented in today's network adapters to help mitigate interrupt overhead in Gigabit-network hosts. In interrupt-coalescing mode, a single interrupt is generated for multiple incoming packets. This is opposed to normal interruption mode in which an interrupt is generate for every incoming packet. It is widely asserted that interrupt coalescing decreases interrupt overhead at the expense of latency. However in this paper, interrupt coalescing is shown to improve latency at high network load. The paper investigates analytically the performance of interrupt coalescing and compares it with that of normal interruption. The paper also proposes a performance-evaluating criterion that integrates a number of performance metrics to compare normal interruption with interrupt coalescing. Analysis shows that a hybrid scheme which combines these two modes can achieve optimal performance.