Performance Effects of Interrupt Throttle Rate on Linux Clusters using Intel Gigabit Network Adapters

Summary form only given. Many high performance computing clusters (HPCC) are still built using gigabit Ethernet as the interconnect connecting all the computing nodes even though there are faster (lower latency and higher bandwidth) alternatives such as Infiniband and Myrinet. The choice of interconnect mainly depends on the parallel application communication characteristics as well as budget requirements since the faster alternatives are much more expensive compared to gigabit Ethernet especially at lower node counts. Some applications require lower latency interconnect since they communicate more frequently but send relatively small messages, and others can be sending infrequent but large messages thus requiring a higher bandwidth interconnect. Since PCs, workstations and servers are designed for server-client type of environment, network interface card (NIC) drivers are usually optimized for specific network traffic patterns by using several interrupt moderation techniques/parameters, specifically interrupt throttle rate (ITR). Since in an HPCC environment the parallel application communication characteristics (i.e. network traffic patterns) are usually different than the default setting, an ITR value has to be identified to achieve best overall system performance for each type of application. This poster will present the case for why this is an important area in high-performance computing clusters connected using gigabit interconnects. It will present methodologies to tune the interrupt throttle rate parameter given to the driver to achieve a balance between application and network performance. Performance results on typical applications will be shown on different clusters