Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Patent
1998-12-23
2000-07-04
Gossage, Glenn
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
711137, 712207, G06F 1200
Patent
active
060852879
ABSTRACT:
The performance of a disk cache subsystem is enhanced by dynamically sizing read requests based upon the current disk cache hit rate. Any data requested in the read request which is not the immediately requested data is located adjacent to the immediately requested data. Accordingly, the size of the read request depends upon at least one variable factor other than the size of the requested data. More specifically, the size of the read request is reduced as the disk cache hit rate declines, and the size of the read request is increased as the disk cache hit rate increases. Short-term and long-term disk cache hit rates are tracked. The short-term disk cache hit rate is used to determine the reduction in the size of the read request, and the long-term disk cache hit rate is used to determine the increase in the size of the read request. The read request is a read-around request formulated to obtain the immediately requested data, plus additional data which is not requested and which is located before and after the immediately requested data. When reading data in a computer system that includes a disk and a disk cache in communication with the disk, the computer system runs an application program which makes a first read request whenever it needs data to execute the program. The first read request is received in a disk cache enhancer and in a disk cache manager. The disk cache manager includes disk cache which is the disk cache of the computer system. The requested data is provided to the application program from the disk cache if the requested data is currently in the disk cache. A second read request is formulated by the disk cache enhancer if the requested data is detected as not currently being in the disk cache. The second read request is the dynamically sized read request. When used in a Windows.RTM. operating system environment, the initial read-around value is about 1 megabyte.
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Israel Ben
O'Neil John T.
Genesis One Technologies, Inc.
Gossage Glenn
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