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Patent Title: Method and system for reissuing load requests in a multi-stream prefetch design

Assignee: IBM
Patent Number: US6317811
Issue Date: 11-13-2001
Application Number: 383737
File Date:08-26-1999


Abstract: A method and system for reissuing load requests in a multi-stream prefetch engine of a data processing system is provided. A read transaction is received from a transaction requester, and the read transaction has a base address and a prefetch stream identifier. The received read transaction is issued to a prefetch stream associated with a data prefetch buffer identified by the prefetch stream identifier as the prefetch stream is one of a set of prefetch streams, each of which has an associated prefetch buffer. The read transaction is issued to a prefetch stream associated with a data prefetch buffer, and a set of prefetch addresses are generated, each prefetch address in the set of prefetch addresses being proximate to the base address. A determination is made as to whether the data prefetch buffer has unallocated prefetch buffer entries, and a comparison is made between each prefetch address in the set of prefetch addresses and all prefetch addresses in each data prefetch buffer to determine whether a prefetch address in the set of prefetch addresses collides with a prefetch address in a data prefetch buffer. In response to a determination of an absence of an address collision and a determination that the data prefetch buffer does not have an unallocated prefetch buffer entry, the base address is held for data prefetch reissuance.

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Link to USPTO

IBM Pledge dated 1/11/2005