Did You Know...
...that the Eveready Battery began as an invention called the "electric flowerpot," which was a tube with a battery and light bulb inside? The idea was to fasten this gizmo to the side of a flowerpot so it would illuminate the flowers from the bottom. The idea died on the vine and the businessman who licensed the flower pot, Conrad Huber, was left with a pile of useless tubes -- until he found a way to market them as batteries to light the world!
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US Patent 6480918 - Lingering locks with fairness control for multi-node computer systems
US Patent Issued on November 12, 2002
Estimated Patent Expiration Date:
December 22, 2018Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
Estimated Patent Expiration Date:
December 22, 2018Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.AbstractThe processors in a multiprocessor computer system are grouped into nodes. The processors can request a lock, but the lock is granted to only one processor at any given time to provide exclusive processor access to the resource protected by the lock. When a processor releases the lock, the lock is made available to another processor at the same node, even though a processor at a different node may have requested the lock earlier. To maintain fairness, the lock is forced to another node after granting a certain number of consecutive requests at a node or after a certain time period. In one embodiment, a specialized data structure representing a lock request from a processor at a particular node is placed into a queue. A later requesting processor can acquire a preemptive position in the queue by spinning on a data structure already in the queue if the data structure corresponds to the processor's node. To maintain fairness, the data structure is limited to a certain number of uses, after which additional processors are not permitted to spin on it. When the data structure has no more active spinners, it is dequeued, and the lock is made available to a processor spinning on the next structure in the queue. Logic for handling interrupts is included, and the bitfield arrangement of the data structure is tailored to the locking scheme. Preallocating data structures for the queue increases performance.Other References
| InventorsApplicationNo. 219229 filed on 12/22/1998US Classes:710/200, ACCESS LOCKING710/240, ACCESS ARBITRATING710/241, Centralized arbitrating710/244, Access prioritizing710/260, INTERRUPT PROCESSING710/263, Interrupt queuing718/104Resource allocationField of Search707/200, FILE OR DATABASE MAINTENANCE707/202, Recoverability710/200, ACCESS LOCKING710/240, ACCESS ARBITRATING710/241, Centralized arbitrating710/244, Access prioritizing710/260, INTERRUPT PROCESSING710/261, Multimode interrupt processing710/262, Interrupt inhibiting or masking710/263, Interrupt queuing710/264Interrupt prioritizingExaminersPrimary: Banankhah, Majid A.Attorney, Agent or FirmUS Patent References5805900, Method and apparatus for serializing resource access requests in a multisystem complexIssued on: 09/08/1998 Inventor: Fagen, et al.6052695, Accurate completion of transaction in cooperative type distributed system and recovery procedure for same Issued on: 04/18/2000 Inventor: Abe, et al.6105085Lock mechanism for shared resources having associated data structure stored in common memory include a lock portion and a reserve portion Issued on: 08/15/2000 Inventor: Farley International ClassesG06F 009/46G06F 013/14 |
