Apparatus and method for performing speculative cache directory tag updates
First Claim
1. A method for operating a computer system, the method comprising the steps of:
- providing a memory storage device, a first control unit, and a memory control unit, the first control unit coupled to the first control unit and a memory control unit, the memory storage device including a first word having tag data;
transmitting the first word from the memory storage device to the first control unit;
transferring the first word from the first control unit to the memory control unit;
generating in the first control unit an updated first word; and
writing the updated first word back to the memory storage device from the first control unit.
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Abstract
An apparatus and method for performing speculative directory cache tag updates for read accesses to memory is herein disclosed. A control unit for performing tag updates is coupled between the memory controller and the memory bank in a multiprocessor system that employs a directory-based coherency protocol. The control unit transmits data read from the memory bank to the memory controller while calculating the updated tag that it then writes back to the memory bank. In this manner, the memory bank busy time and memory bus traffic are reduced thereby improving the overall performance of a memory access.
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Citations
9 Claims
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1. A method for operating a computer system, the method comprising the steps of:
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providing a memory storage device, a first control unit, and a memory control unit, the first control unit coupled to the first control unit and a memory control unit, the memory storage device including a first word having tag data;
transmitting the first word from the memory storage device to the first control unit;
transferring the first word from the first control unit to the memory control unit;
generating in the first control unit an updated first word; and
writing the updated first word back to the memory storage device from the first control unit. - View Dependent Claims (2, 3, 4, 5)
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6. A computer system, comprising:
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a memory storage device including a plurality of words, a first word having a tag portion; and
a first control unit, coupled to the memory storage device, including;
a first logic unit to determine when the first word is read from the memory storage device;
a second logic unit that updates the tag portion of the first word when the first logic unit determines that the first word is read from the memory storage device;
a third logic unit that generates an updated first word based on the updated tag portion; and
a fourth logic unit that writes the updated first word back to the memory storage device. - View Dependent Claims (7, 8, 9)
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Specification