Method and a system for determining an appropriate amount of data to cache
First Claim
1. A method for determining an appropriate amount of data to stage in cache memory in a data processing comprising the steps of:
- a) determining a history of data accessing and storage on a disk, the disk including a plurality of regions, each of the plurality of regions having at least one sub-region, wherein each of the plurality of regions is associated with a plurality of counters, each of the plurality of counters corresponding to one the plurality of staging modes, the step of determining a history further comprising the steps of;
a1) determining which one of the plurality of staging modes should have been used based upon a data reference type; and
a2) incrementing a counter, the counter being one of the plurality of counters associated with the region and corresponding to the one of the plurality of staging methods that should have been used;
b) maintaining within a cache directory a data structure for each of the plurality of sub regions, said data structure comprising;
b1) a data segment identifier of an originally referenced data segment; and
b2) a plurality of indicators;
wherein, a first indicators of the plurality of indicators is set when a current reference is to a data segment positioned in the sub-region after the originally referenced data segment, and a second indicator is set when a current reference is to a data segment positioned in the sub-region before the originally referenced data segment, for establishing the data reference type; and
c) predicting an optimal staging mode from a plurality of staging modes based upon the history.
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Abstract
A method and a system for determining how much data to cache, that is, optimizing disk caching control by selecting the optimal staging mode are disclosed. Specifically, the method and system of the present invention provides an analytical framework for determining how much data to cache thus producing a maximum hit rate and optimal utilization of computer system resources. The method and system in accordance with the present invention includes determining a history of referencing data on a disk and predicting an optimal staging mode from a plurality of staging modes based upon the history. The method and system of the present invention in the preferred embodiment allow staging in one of at least three modes: record staging, staging to the end of track, and full track staging. In using the history of data referencing to predict the optimal staging mode, the method and system of present invention provide a thorough analytical framework for determining which of the modes of staging data is most desirable in view of prior referencing patterns.
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Citations
15 Claims
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1. A method for determining an appropriate amount of data to stage in cache memory in a data processing comprising the steps of:
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a) determining a history of data accessing and storage on a disk, the disk including a plurality of regions, each of the plurality of regions having at least one sub-region, wherein each of the plurality of regions is associated with a plurality of counters, each of the plurality of counters corresponding to one the plurality of staging modes, the step of determining a history further comprising the steps of; a1) determining which one of the plurality of staging modes should have been used based upon a data reference type; and a2) incrementing a counter, the counter being one of the plurality of counters associated with the region and corresponding to the one of the plurality of staging methods that should have been used; b) maintaining within a cache directory a data structure for each of the plurality of sub regions, said data structure comprising; b1) a data segment identifier of an originally referenced data segment; and b2) a plurality of indicators;
wherein, a first indicators of the plurality of indicators is set when a current reference is to a data segment positioned in the sub-region after the originally referenced data segment, and a second indicator is set when a current reference is to a data segment positioned in the sub-region before the originally referenced data segment, for establishing the data reference type; andc) predicting an optimal staging mode from a plurality of staging modes based upon the history. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification