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  The experiments reported in this paper give a quantitative snapshot of the state of the art for TCP/IP networking performance on current-generation desktop-class PCs and workstations and gigabit-per-second networks.

Our measurements are taken from the standard high-quality TCP/IP implementation in the FreeBSD 4.0 kernel, supplemented with support for a range of techniques to reduce communication overheads. These include zero-copy sockets and several features implemented in the Trapeze firmware for Myrinet, including large MTUs with scatter/gather I/O, page-aligned payload buffers, adaptive message pipelining, interrupt suppression, and checksum offloading. With these features, we have measured TCP/IP bandwidths of 956 Mb/s using Trapeze/Myrinet and 988 Mb/s using an Alteon Gigabit Ethernet network. These are the highest TCP bandwidths on public record at present. The 500 MHz Alpha 21264 platform is capable of handling these bandwidths with CPU overheads as low as 20%.

Jeff Chase