Amazon.com, Inc.
Synchronization of DMA transfers for large number of queues

Abstract:

Synchronization of a plurality of aggregate DMA transfers on large number of DMA queues can be achieved using a small number of semaphores. One or more semaphores from M semaphores can be assigned to each aggregate DMA transfer based on round-robin or another suitable method. Each aggregate DMA transfer can comprise N DMA transfers, where M is smaller than N. Each DMA transfer can be assigned to one of the assigned one or more semaphores from the M semaphores. Each DMA engine of N DMA engines can increment the assigned semaphore after performing a respective DMA transfer of the N DMA transfers. A computational engine waiting on completion of a certain aggregate DMA transfer can perform an operation based upon the one or more assigned semaphores reaching respective threshold values.