Electrical computers and digital processing systems: memory – Storage accessing and control – Shared memory area
Reexamination Certificate
2005-05-24
2005-05-24
Padmanabhan, Mano (Department: 2188)
Electrical computers and digital processing systems: memory
Storage accessing and control
Shared memory area
C711S130000, C711S141000, C711S142000, C711S143000, C711S146000
Reexamination Certificate
active
06898676
ABSTRACT:
A computer system supports a first set of processors configured to operate in a dirty-shared mode and a second set of processors configured to operate in a non dirty-shared mode. The computer system may include a portion of shared memory that stores data in terms of memory blocks. Upon receiving a snoop read requesting shared access to a memory block held in a dirty state, a dirty-shared processor sends a copy of the memory block to the originator of the snoop read and retains a valid a copy of the block in its cache. Non dirty-shared processors additionally write the block back to main memory in response to snoop reads and may also send a copy to the originator. Until the write back is completed at main memory or another processor is granted write access to the block, the dirty-shared and non dirty-shared processors preferably continue to satisfy sub-sequent snoop reads targeting the memory block.
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Tierney Gregory E.
Van Doren Stephen R.
Hewlett--Packard Development Company, L.P.
Namazi Mehdi
Padmanabhan Mano
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