US5386546A
Expired / Lapsed
US
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Block substitution method in a cache memory of a multiprocessor system
Assignee: Canon Inc
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Filing: 1991-11-27
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Granted: 1995-01-31
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Expires: 2011-11-27
Abstract
Abstract A block substitution method of a cache memory incudes the steps of storing data integrity information with a main memory for each block of the cache memory and calculating a non-reference period of each block. The non-reference periods of the blocks are compared to determine an order of the blocks based on the non-reference periods and a difference between the non-reference period of the block having a longest non-reference period and the non-reference period of other blocks is calculated. Data integrity in the block having the longest non-reference period is examined and when there is no data integrity in that block the data integrity in other blocks is examined in the order of the non-reference period. A block having a longest non-reference period among the blocks having the data integrity is determined and the determined block is selected as a block to be substituted by a new data block when the difference is smaller than a predetermined value. New data is loaded to the selected block.
Inventors
- 👤 Kazumasa Hamaguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:27
CPC Classifications
G; G06; G06F; G06F12/00; G06F12/02; G06F12/08; G06F12/12; G06F12/121; G06F12/123; G06F12/126; G06F12/127; G06F12/0802; G06F12/0804; G06F12/0806; G06F12/0815; G06F12/0831
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
160 words
A block substitution method of a cache memory comprising the steps of: storing data integrity information with a main memory for each block of the cache memory; calculating a non-reference period of each block; comparing the non-reference periods of the blocks to determine an order of the blocks based on the non-reference periods; calculating a difference between the non-reference period of the block having a longest non-reference period and the non-reference period of other blocks; examining data integrity in the block having the longest non-reference period; examining the data integrity in other blocks in the order of non-reference period when there is no data integrity in the block having the longest non-reference period; determining a block having a longest non-reference period among the blocks having the data integrity; selecting the determined block as a block to be substituted by a new data block when the difference is smaller than a predetermined value; and loading new data to the selected block.
Claim 2
Dependent Claim
160 words
A block substitution method of a cache memory comprising the steps of: storing data integrity information with a main memory for each block of the cache memory; calculating a non-reference period of each block; comparing the non-reference periods of the blocks to determine an order of the blocks based on the non-reference periods; calculating a difference between the non-reference period of the block having a longest non-reference period and the non-reference period of other blocks; examining data integrity in the block having the longest non-reference period; examining the data integrity in other blocks in the order of non-reference period when there is no data integrity in the block having the longest non-reference period; determining a block having a longest non-reference period among the blocks having the data integrity; selecting the determined block as a block to be substituted by a new data block when the difference is smaller than a predetermined value; and loading new data to the selected block.
Claim 3
Dependent Claim
54 words
A block substitution method according to claim 1 further comprising a step of selecting the block having the longest non-reference period among all blocks as the block to be substituted when the difference of the block having the longest non-reference period among the blocks having the data integrity is larger than the predetermined value.
Claim 4
Dependent Claim
40 words
A block substitution method according to claim 1, wherein the block having the longest non-reference period among all blocks is selected as the block to be substituted when there is no data integrity in all blocks of the cache memory.
Claim 5
Dependent Claim
114 words
A block substitution method of a cache memory comprising the steps of: storing status information indicating whether or not a block is to be written in a main memory for each block of the cache memory; storing time stamp information indicating a last time a block was used, for each block of the cache memory; calculating a non-reference period of each block based on the time stamp; selecting a block having a longest non-reference period among the blocks not to be written in the main memory based on the status information and the non-reference period; and substituting new data for the data in the selected block by loading new data to the selected block.
Claim 6
Dependent Claim
114 words
A block substitution method of a cache memory comprising the steps of: storing status information indicating whether or not a block is to be written in a main memory for each block of the cache memory; storing time stamp information indicating a last time a block was used, for each block of the cache memory; calculating a non-reference period of each block based on the time stamp; selecting a block having a longest non-reference period among the blocks not to be written in the main memory based on the status information and the non-reference period; and substituting new data for the data in the selected block by loading new data to the selected block.
Claim 7
Dependent Claim
35 words
A block substitution method according to claim 4, further comprising a step of calculating a difference between the non-reference period of the block having a longest non-reference period and the non-reference period of other blocks.
Claim 8
Dependent Claim
43 words
A block substitution method according to claim 5, wherein the block having the longest non-reference period among the blocks not to be written in the main memory is not selected if the difference corresponding to the block is larger than a predetermined value.
Claim 9
Dependent Claim
30 words
A block substitution method according to claim 6, wherein the block having the longest non-reference period among all blocks is selected if the difference is larger than the predetermined value.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-01-30 | 1998-08-01 | 1999-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-30 | 2002-08-01 | 2003-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-30 | 2006-08-01 | 2007-01-31 | $7700.00 | Window Closed / Lapsed |