Apparatus and method for managing work and completion queues using head and tail pointers with end-to-end context error cache for reliable datagram

摘要

An apparatus and method for managing reliable datagram work queues, and associated completion queues, using head and tail pointers with end-to-end context error cache are provided. With the apparatus and method, reliable datagram (RD) queue head and tail pointers are maintained in the channel interface and the host channel adapter. The head and tail pointers in the host channel adapter include a RD queue page table index and a RD queue page index for identifying a position within the RD queue. For RD work queues, the tail pointer in the channel interface is used to identify a next position where a work queue entry may be written. The head pointer in the channel interface is used only to determine whether the work queue is full or not. The head pointer in the host channel adapter is used to identify a next work queue entry for processing by the host channel adapter. The tail pointer in the host channel adapter is used by the host channel adapter to determine if the queue is empty.