Barrier and Interrupt Mechanism for High Latency and Out of Order DMA Device

A method in a direct memory access engine in a direct memory access device for performing a direct memory access block move, the method comprising:

• receiving a direct memory access block move descriptor, wherein the direct memory access block move descriptor indicates a source and a target and wherein the direct memory access block move request is identified as a barrier descriptor;
• converting the direct memory access block move descriptor into one or more direct memory access requests for the direct memory access block move descriptor;
• identifying a last direct memory access request within the one or more direct memory access requests;
• setting a barrier attribute associated with the last direct memory access request;
• and
• for each given direct memory access request in the one or more direct memory access requests:
• determining whether the barrier attribute is set for the given direct memory access request;
• if the barrier attribute is set, determining whether a barrier is pending for a channel associated with the given direct memory access request;
• and
• if a barrier is not pending for the channel associated with the given direct memory access request, issuing the given direct memory access request to a bus engine in the direct memory access device.

A method in a bus engine in a direct memory access device for performing a direct memory access block move, the method comprising:

• receiving a direct memory access request from a direct memory access queue;
• determining whether the direct memory access request has a barrier attribute set;
• if the direct memory access request has a barrier attribute set, determining whether all direct memory access requests before the barrier have completed;
• and
• if all direct memory access requests before the barrier have not completed, holding the direct memory access request from completing.

A direct memory access device, comprising:

• a direct memory access engine, wherein the direct memory access engine is configured to:
• receive a direct memory access block move descriptor, wherein the direct memory access block move descriptor indicates a source and a target and wherein the direct memory access block move request is identified as a barrier descriptor;
• convert the direct memory access block move descriptor into one or more direct memory access requests for the direct memory access block move descriptor;
• identify a last direct memory access request within the one or more direct memory access requests;
• set a barrier attribute associated with the last direct memory access request;
• and
• issue the one or more direct memory access requests to a direct memory access queue;
• and
• a bus engine, wherein the bus engine is configured to:
• receive a direct memory access request from a direct memory access queue;
• determine whether the direct memory access request has a barrier attribute set;
• if the direct memory access request has a barrier attribute set, determine whether all direct memory access requests before the barrier have completed;
• and
• if all direct memory access requests before the barrier have not completed, hold the direct memory access request from completing.