Electrical computers and digital processing systems: memory – Storage accessing and control – Hierarchical memories
Reexamination Certificate
2007-01-10
2009-10-06
Elmore, Reba I (Department: 2189)
Electrical computers and digital processing systems: memory
Storage accessing and control
Hierarchical memories
Reexamination Certificate
active
07600077
ABSTRACT:
Cache circuitry, a data processing apparatus including such cache circuitry, and a method of handling write requests within cache circuitry, are provided. The cache circuitry has a plurality of slots, with each slot arranged to store attributes associated with a pending access request. A record of identifiers that are available to associate with pending access requests is maintained, and control circuitry is responsive to an access request issued by a device to accept that access request as a pending access request by allocating one of the slots to that access request, obtaining one of said identifiers from the record to associate with that access request, and causing the attributes associated with that access request to be stored in the allocated slot along with the obtained identifier. A check procedure is performed to determine, for each pending access request, whether that access request is allowed to proceed. For a speculative pending write access request that is determined to be allowed to proceed, the attributes associated with that access request and the identifier associated with that access request are transferred from the allocated slot to a write entry within a write access buffer, after which the allocated slot is freed for allocation to a subsequent access request. When a speculative confirmed signal is then received from the device specifying that identifier, the write access buffer outputs the attributes from the write entry to store circuitry used to complete the access request. This provides a very efficient mechanism for handling speculative write accesses within a cache.
REFERENCES:
patent: 2006/0143384 (2006-06-01), Hughes et al.
patent: 2006/0174062 (2006-08-01), Bockhaus
Begon Florent
Charra Elodie
Chaussade Nicolas
Luc Philippe
ARM Limited
Elmore Reba I
Nixon & Vanderhye P.C.
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