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 Title: |
US6820142:
Token based DMA
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Hofstee, Harm Peter; Austin, TX
Nair, Ravi; Briarcliff Manor, NY
Wellman, John-David; Peekskill, NY
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| Assignee: |
International Business Machines Corporation, Armonk, NY
other patents from INTERNATIONAL BUSINESS MACHINES CORPORATION (280070) (approx. 44,393)
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| Published / Filed: |
2004-11-16
/ 2000-12-14
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| Application Number: |
US2000000736356
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| IPC Code: |
Advanced:
G06F 13/28;
Core:
G06F 13/20;
IPC-7:
G06F 13/28;
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| ECLA Code: |
G06F13/28;
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| U.S. Class: |
710/025;
710/023;
710/028;
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| Field of Search: |
710/023,28,22
711/005,147-152,163
370/230,395.42,369,375-379
345/560
709/230
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| Priority Number: |
| 2000-12-14 |
US2000000736356 |
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| Abstract: |
A method and system for accessing a shared memory in a deterministic schedule. In one embodiment, a system comprises a plurality of processing elements and a system I/O controller where each processing element and system I/O controller comprises a DMA controller. The system further comprises a shared memory coupled to each of the plurality of processing elements where the shared memory comprises a master controller. The master controller may then issue tokens to DMA controllers to grant the right for the associated processing elements and system I/O controller to access the shared memory at deterministic points in time. Each token issued by the master controller grants access to the shared memory for a particular duration of time at a unique deterministic point in time. A processing element or system I/O controller may access the shared memory upon the associated DMA controller relinquishing to the master controller the token that grants the right to access the shared memory at that particular time. The master controller may then reissue the relinquished token back to the DMA controller associated with the processing element or system I/O controller that accessed the shared memory if at a future designated time, e.g., 128 ns from the completion of the access to the shared memory, there does not exist a higher prioritized request, e.g., refresh the shared memory, to access the shared memory at that future designated time. The reissued token grants the right to access the shared memory at the future designated time.
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| Attorney, Agent or Firm: |
Voigt, Jr., Robert A.Winstead Sechrest & Minick P.C. ;
Salys, Casimer K. ;
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| Primary / Asst. Examiners: |
Gaffin, Jeffrey; Schneider, Joshua D
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| INPADOC Legal Status: |
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| Parent Case: |
CROSS REFERENCE TO RELATED APPLICATIONS
The present invention is related to the following U.S. patent applications which are incorporated herein by reference:
Ser. No. 09/736,452 entitled "Reduction of Interrupts in Remote Procedure Calls" filed Dec. 14, 2000.
Ser. No. 09/736,585 entitled "Symmetric Multi-Processing System" filed Dec. 14, 2000.
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| Family: |
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First Claim:
Show all 20 claims |
What is claimed is:
1. A system comprising:
- a plurality of processing elements, wherein each processing element of said plurality of processing elements comprises a direct memory access controller, and
- a shared memory coupled to said plurality of processing elements, wherein said shared memory comprises a master controller, wherein said master controller is operable for issuing tokens to direct memory access controllers for accessing said shared memory at deterministic points in time.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 6 U.S. patent(s) that reference this one
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