International Business Machines Corporation

Peichun Peter Lui

Jieming Qi

David Mui

Matthew Edward King

An improved DMAC translation mechanism is presented. DMA commands are 'unrolled' based upon the transfer size of the DMA command and the amount of data that a computer system transfers at one time. For the first DMA request, a DMA queue requests a memory management unit to perform an address translation. The DMA queue receives a real page number from the MMU and, on subsequent rollout requests, the DMA queue provides the real page number to a bus interface unit without accessing the MMU until the transfer crosses into the next page. Rollout logic decrements the DMA command's transfer size after each DMA request, determines whether a new page has been reached, determines if the DMA command is completed, and sends write back information to the DMA queue for subsequent DMA requests.

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Austin, TX, United States of America

Peichun Peter Lui