Patent ID: 8490113

Claim:
An apparatus for messaging in a parallel computer using remote direct memory access (‘RDMA’), the parallel computer including a plurality of nodes, each node including a messaging unit, the apparatus comprising a computer processor, a computer memory operatively coupled to the computer processor, the computer memory having disposed within it computer program instructions that, when executed by the processor, cause the apparatus to carry out the steps of: receiving, by a kernel of the first node through an application programming interface (‘APF’), a send work request, the send work request including: a local virtual address on the first node from which data is to be transferred; and a specification of a size of data to be transferred from the first node to a second node, wherein the size of data to be transferred from the first node to a second node is larger than a messaging packet size for sending data from the first node to a second node; responsive to the send work request: translating, by the kernel of the first node, the local virtual address on the first node from which data is to be transferred to a physical address on the first node from which data is to be transferred from; creating, by the kernel of the first node, a local RDMA object that includes a counter set to the size of a messaging acknowledgment field; sending, from a messaging unit in the first node to a messaging unit in a second node, a message that includes a RDMA read operation request, the physical address of the local RDMA object, and the physical address on the first node from which data is to be transferred from; and receiving, by the first node responsive to the second node's execution of the RDMA read operation request, acknowledgment data in the local RDMA object.