EP0373780A2
Expired / Lapsed
EP
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Address translation for multiple-sized pages
Assignee: International Business Machines Corp
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Filing: 1989-11-23
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Granted: —
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Expires: 2009-11-23
Abstract
Abstract In a data processing system including bulk storage and paging storage, a two 64-pair DLAT structure is used, one for 4KB pages and one for 1MB pages. Each DLAT is two-way set associative with pairs of entries, each entry representing a page. The DLATs are interrogated in parallel by a hash combination of appropriate intermediate virtual address bit and each entry includes a high order page identifier, a real address and a valid bit, access being provided to the real address if the identifier and the valid bit are both satisfied. There is no page overlap.
Inventors
- 👤 Steven Wayne White
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 06:01
CPC Classifications
G; G06; G06F; G06F12/00; G06F12/02; G06F12/08; G06F12/10; G06F12/1027; G06F12/1036; G06F2212/00; G06F2212/65; G06F2212/652
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
125 words
Data storage apparatus having memory, an external data transfer interface and an external demand interface and control logic whereby data requests received over the demand interface are immediately satisfied from memory or are satisfied from memory after data transfer over the external data transfer interface, the unit of data transfer being a page and at least some of the resident pages being identifiable by reference to directory look-aside tables DLAT maintained by the control logic, wherein a currently transferred page can be of one of a predetermined plurality of sizes, the control logic maintaining one independent DLAT for each page size in a manner that permits parallel interrogation of all potentially appropriate DLAT entries when attempting to provide immediate satisfaction of a received data request.
Claim 2
Dependent Claim
125 words
Data storage apparatus having memory, an external data transfer interface and an external demand interface and control logic whereby data requests received over the demand interface are immediately satisfied from memory or are satisfied from memory after data transfer over the external data transfer interface, the unit of data transfer being a page and at least some of the resident pages being identifiable by reference to directory look-aside tables DLAT maintained by the control logic, wherein a currently transferred page can be of one of a predetermined plurality of sizes, the control logic maintaining one independent DLAT for each page size in a manner that permits parallel interrogation of all potentially appropriate DLAT entries when attempting to provide immediate satisfaction of a received data request.
Claim 3
Dependent Claim
35 words
Apparatus as claimed in claim 1, wherein the maintained DLATs are set-associative and the control logic automatically combines different portion of the address of the current data request for set determination appropriate to each DLAT.
Claim 4
Dependent Claim
50 words
Apparatus as claimed in claim 2, wherein each DLAT entry in each set includes a distinctive array of the remaining request address data appropriate to the associated resident page to which compare means in the control logic is responsive for partial access enabling and the real address of that page.
Claim 5
Dependent Claim
28 words
Apparatus as claimed in claim 3, wherein each DLAT entry in each set includes a "valid" bit, partially enabling access to the contents of the indicated real page.
Claim 6
Dependent Claim
23 words
Apparatus as claimed in claim 4, wherein the control logic concatenates, to the real address an off-set portion of the request address data.
Claim 7
Dependent Claim
37 words
Apparatus as claimed in claim 5, wherein there is a page size corresponding to the virtual address spectrum segment size - say, 1MB - and a page size corresponding to the memory frame size - say, 4KB.
Claim 8
Dependent Claim
22 words
A storage sub-system including apparatus as claimed in any preceding claim and bulk storage devices connected to the external data transfer interface.
Claim 9
Dependent Claim
16 words
A sub-system as claimed in claim 7, wherein the page data is stored on appropriate boundaries.
Claim 10
Dependent Claim
40 words
A data processing system including a sub-system as claimed in claim 7 or claim 8, having a processor connected to the external demand interface thereof, the system being arranged so that there is no page overlap, irrespective of page size.
Claim 11
Independent Claim
120 words
A method of providing addressability to data pages of differing predetermined sizes in a data processing system having bulk storage and paging storage, wherein data is requested by virtual address and the paging storage is accessed by real address, comprising allocating pages with no overlap; maintaining a DLAT for each page size; maintaining set associative addressability in parallel to each DLAT; and providing a within-set page identifier, a real address and a validity identification for each entry within each set within each DLAT whereby, if a page containing requested data is resident in paging storage and has been sufficiently recently active, one and only one DLAT will respond to the parallel interrogation providing rapid unique access to the sought page.
Claim 12
Independent Claim
120 words
A method of providing addressability to data pages of differing predetermined sizes in a data processing system having bulk storage and paging storage, wherein data is requested by virtual address and the paging storage is accessed by real address, comprising allocating pages with no overlap; maintaining a DLAT for each page size; maintaining set associative addressability in parallel to each DLAT; and providing a within-set page identifier, a real address and a validity identification for each entry within each set within each DLAT whereby, if a page containing requested data is resident in paging storage and has been sufficiently recently active, one and only one DLAT will respond to the parallel interrogation providing rapid unique access to the sought page.
References Cited (Backward Citations)
No citation records indexed.
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