Invention Grant
US07620749B2 Descriptor prefetch mechanism for high latency and out of order DMA device
有权
高延迟和无序的DMA设备的描述符预取机制
- Patent Title: Descriptor prefetch mechanism for high latency and out of order DMA device
- Patent Title (中): 高延迟和无序的DMA设备的描述符预取机制
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Application No.: US11621789Application Date: 2007-01-10
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Publication No.: US07620749B2Publication Date: 2009-11-17
- Inventor: Giora Biran , Luis E. De la Torre , Bernard C. Drerup , Jyoti Gupta , Richard Nicholas
- Applicant: Giora Biran , Luis E. De la Torre , Bernard C. Drerup , Jyoti Gupta , Richard Nicholas
- Applicant Address: US NY Armonk
- Assignee: International Business Machines Corporation
- Current Assignee: International Business Machines Corporation
- Current Assignee Address: US NY Armonk
- Agent Stephen R. Tkacs; Stephen J. Walker, Jr.; Matthew B. Talpis
- Main IPC: G06F13/28
- IPC: G06F13/28

Abstract:
A DMA device prefetches descriptors into a descriptor prefetch buffer. The size of descriptor prefetch buffer holds an appropriate number of descriptors for a given latency environment. To support a linked list of descriptors, the DMA engine prefetches descriptors based on the assumption that they are sequential in memory and discards any descriptors that are found to violate this assumption. The DMA engine seeks to keep the descriptor prefetch buffer full by requesting multiple descriptors per transaction whenever possible. The bus engine fetches these descriptors from system memory and writes them to the prefetch buffer. The DMA engine may also use an aggressive prefetch where the bus engine requests the maximum number of descriptors that the buffer will support whenever there is any space in the descriptor prefetch buffer. The DMA device discards any remaining descriptors that cannot be stored.
Public/Granted literature
- US20080168259A1 Descriptor Prefetch Mechanism for High Latency and Out of Order DMA Device Public/Granted day:2008-07-10
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