The Trapeze messaging system consists of two components: a messaging library that is linked into programs using the package, and a firmware program that runs on the Myrinet network interface card (NIC). The Trapeze firmware and the host interact by exchanging commands and data through a block of memory on the NIC, which is addressable in the host's physical address space using programmed I/O. The firmware defines the interface between the host CPU and the network device; it interprets commands issued by the host and controls the movement of data between the host and the network link. The host accesses the network using macros and procedures in the Trapeze library, which defines the lowest level API for network communication across the Myrinet.
Like other network interfaces based on Myrinet (e.g., Hamlyn [4], VMMC-2 [13], Active Messages [9], FM [21]), Trapeze can be used as a memory-mapped network interface for user applications, e.g., parallel programs. However, Trapeze was designed primarily to support fast kernel-to-kernel messaging alongside conventional TCP/IP networking. The Trapeze distribution includes a network device driver that allows the native TCP/IP protocol stack to use a Trapeze network alongside the gms_net layer. Figure 1 depicts this structure. The kernel-to-kernel messaging layer is intended for GMS and other services that assume mutually trusting kernels.
