Patent EP0220451A2 successfully refreshed from Google Patents.
EP0220451A2
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EP
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A cache coherence mechanism based on locking
Assignee: International Business Machines Corp
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Filing: 1986-09-12
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Granted: —
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Expires: 2006-09-12
Abstract
Abstract A method and apparatus is provided for associating in cache directories the Control Domain Identifications (CDIDs) of software covered by each cache line. Through the use of such provision and/or the addition of Identifications of users actively using lines, cache coherence of certain data is controlled without performing conventional Cross-Interrogates (XIs), if the accesses to such objects are properly synchronized with locking type concurrency controls. Software protocols to caches are provided for the resource kernel to control the flushing of released cache lines. The parameters of these protocols are high level Domain Identifications and Task Identifications.
Inventors
- 👤 Lishing Liu
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 15:44
CPC Classifications
G; G06; G06F; G06F12/00; G06F12/02; G06F12/08; G06F12/0802; G06F12/0806; G06F12/0815; G06F12/0837
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
199 words
A method of cache control for maintaining cache coherence in a multiprocessing system comprised of a plurality of processors (2,4,6,8) which share a main storage (10), with each processor having a cache (40) and a directory (42) with a plurality of line entries of information, with a block of information being comprised of at least one line, characterized in that a control domain (CD) being defined as at least one of said blocks of information, with each line entry including a CD identification (CDID) flag to identify the CD to which a line belongs, said method comprising the steps of: setting said CDID flag, of any line of information transferred from said main storage (10) to said cache, to a selected state which identifies the CD to which said any line is associated with; issuing a FLUSH command, including a predetermined CDID flag, by a given processor to remove a line of information with said predetermined CDID from the associated cache; and comparing the CDID in the FLUSH command with the CDID of the lines of information in the associated cache, and if a match of CDID's is found, removing the line with the matched CDID from said cache.
Claim 2
Independent Claim
199 words
A method of cache control for maintaining cache coherence in a multiprocessing system comprised of a plurality of processors (2,4,6,8) which share a main storage (10), with each processor having a cache (40) and a directory (42) with a plurality of line entries of information, with a block of information being comprised of at least one line, characterized in that a control domain (CD) being defined as at least one of said blocks of information, with each line entry including a CD identification (CDID) flag to identify the CD to which a line belongs, said method comprising the steps of: setting said CDID flag, of any line of information transferred from said main storage (10) to said cache, to a selected state which identifies the CD to which said any line is associated with; issuing a FLUSH command, including a predetermined CDID flag, by a given processor to remove a line of information with said predetermined CDID from the associated cache; and comparing the CDID in the FLUSH command with the CDID of the lines of information in the associated cache, and if a match of CDID's is found, removing the line with the matched CDID from said cache.
Claim 3
Dependent Claim
95 words
The method of claim 1, wherein each line of information includes a change (CH) flag which in one state is indicative of having been changed and when in another state is indicative of not being changed, and said flush command including a modify (M) flag which indicates in one state that said FLUSH command operates only on modified lines in said cache, and including the step of: removing said line of information from said cache only when said M flag is in said one state concurrent with said CH flag being in said one state.
Claim 4
Dependent Claim
73 words
The method of claim 2, wherein a user identification (UID) flag is assigned to each system user of the respective lines of information stored in said first level memories to identify if one or more users are utilizing the same line of information, said method including the step of: responding to said FLUSH command by a cache only if all UID's indicate that no use is being made of said line of information.
Claim 5
Independent Claim
53 words
The method of claims 3, including the step of indicating a given user identification (UIDC) flag in a line of information is made invalid if said UIDC flag is in a line of information in which the CDID and CH flag match with the CDID and M Flag, respectively, of the FLUSH command.
References Cited (Backward Citations)
No citation records indexed.
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