One of the most CPU intensive activities associated with performing network protocol processing is the need to copy incoming network data from an initial landing point in system memory to a final destination in application memory. This copying is necessary because received network data cannot generally be moved to the final destination until the associated packets are: A) analyzed to ensure that they are free of errors, B) analyzed to determine which connection they are associated with, and C) analyzed to determine where, within a stream of data, they belong. Until recently, these steps had to be performed by the host protocol stack. With the introduction of the intelligent network interface device (as disclosed in U.S. patent application Ser. Nos. 09/464,283, 09/439,603, 09/067,544, and U.S. Provisional Application Ser. No. 60/061,809), these steps may now be performed before the packets are delivered to the host protocol stack.
Even with such steps accomplished by an intelligent network interface device, there is another problem to be addressed to reduce or eliminate data copying, and that is obtaining the address of the destination in memory and passing that address to the network interface device. Obtaining this address is often difficult because many network applications are written in such a way that they will not provide the address of the final destination until notified that data for the connection has arrived (with the use of the “select( )” routine, for example). Other attempts to obtain this address involve the modification of existing applications. One such example is the Internet Engineering Task Force (IETF) Remote DMA (RDMA) proposal, which requires that existing protocols such as NFS, CIFS, and HTTP be modified to include addressing information in the protocol headers. A solution is desired that does not require the modification of existing applications or protocols.