Remote measurement of interrupt-coalescence latency of internet hosts

Interrupt coalescence (IC) in the network interface card (NIC) of an Internet host is a hardware artifact to reduce the processing load of the host, but it also adds an additional delay in the processing time of a packet. As the transmission speeds of Internet hosts are increasing at a faster pace than the processing speeds of the hosts, NICs running at 100 Mb/s and above are adopting IC. This added delay from IC incurs a significant error to the measurement of various network parameters performed by Internet hosts. Knowledge of the IC-based delay helps to increase the accuracy of the measurement of several network parameters, including delay and bandwidth, and supports delay-sensitive applications, such as IP geolocation and load balancing. In this paper, we propose a scheme to measure the IC period of a remote Internet hosts using pairs of probing packets. The scheme does not require infrastructural support along the path or specialized instrumentation at the host under test. We evaluated the scheme on a testbed and an open-access campus network, on links of up to 1000 Mb/s. The scheme measures the IC period with 90% accuracy, quickly, and with a small probing load.