A Transport-Friendly NIC for Multicore/Multiprocessor Systems

Receive side scaling (RSS) is an NIC technology that provides the benefits of parallel receive processing in multiprocessing environments. However, RSS lacks a critical data steering mechanism that would automatically steer incoming network data to the same core on which its application thread resides. This absence causes inefficient cache usage if an application thread is not running on the core on which RSS has scheduled the received traffic to be processed and results in degraded performance. To remedy the RSS limitation, Intel´s Ethernet Flow Director technology has been introduced. However, our analysis shows that Flow Director can cause significant packet reordering. Packet reordering causes various negative impacts in high-speed networks. We propose an NIC data steering mechanism to remedy the RSS and Flow Director limitations. This data steering mechanism is mainly targeted at TCP. We term an NIC with such a data steering mechanism “A Transport-Friendly NIC” (A-TFN). Experimental results have proven the effectiveness of A-TFN in accelerating TCP/IP performance.