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Abstract : |
The SHRIMP multicomputer provides virtual memorymapped communication (VMMC), which supports protected, user-level message passing, allows user programs to perform their own buffer management, and separates data transfers from control transfers so that a data transfer can be done without the intervention of the receiving node CPU. An important question is whether such a mechanism can indeed deliver all of the available hardware performance to applications which use conventional message-passing libraries. This paper reports our early experience with messagepassing on a small, working SHRIMP multicomputer. We have implemented several user-level communication libraries on top of the VMMC mechanism, including the NX messagepassing interface, Sun RPC, stream sockets, and specialized RPC. The first three are fully compatible with existing systems. Our experience shows that the VMMC mechanism supports these message-passing interfaces well. When zerocopy protocols are allowed by the semantics of the interface, VMMC can effectively deliver to applications almost all of the raw hardware's communication performance. 1, |
