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. 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, in the channel interface, the tail pointer is used to identify a next position where a work queue entry may be written and the head pointer is used only to determine whether the work queue is full. In the host channel adapter, the head pointer is used to identify a next work queue entry for processing and the tail pointer is used to determine if the queue is empty.