Advanced contention detection
First Claim
1. A method of detecting contention in addressed memory updating in which a memory location having a specific location identifier can be updated substantially simultaneously from a plurality of sources, said method comprising the steps of:
- (i) utilizing an updating format for the signal or packet carrying out the updating, said format comprising the specific identifier of the memory location to be updated, the content with which said memory location is to be updated, and a resident updating count of the updating source, said count comprising a number indicative of the position of the updating message in the sequence of occasions on which the updating source has been updated inclusive of the current updating;
(ii) storing for each receiving memory location the updating count of the previously received updating;
(iii) comparing the updating count presently resident at the receiving memory location with the updating count of any currently received updating signal or packet; and
(iv) indicating a contention situation if the compared updating counts are the same.
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Abstract
A multiple computer system is disclosed in which n computers (M1, M2 . . . Mn) each run a different portion of a single application program written to execute only on a single computer. The local memory of each computer is maintained substantially the same by updating all computers with every change made to addressed memory locations. Contention can arise when the same memory location is substantially simultaneously updated by two or more machines because of transmission delays and latency of the communications network interconnecting all the computers. Contention detection and resolution is disclosed. A count value (99) indicative of the cumulative number of times each memory location has been updated is utilized. Contention is indicated if the currently stored count value and the incoming updating count value are the same. A method of echo suppression and a method of echo rejection are disclosed. In particular incrementing the count value by two in the case of consecutive sequential transmission to the same memory location (D) is disclosed.
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Citations
13 Claims
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1. A method of detecting contention in addressed memory updating in which a memory location having a specific location identifier can be updated substantially simultaneously from a plurality of sources, said method comprising the steps of:
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(i) utilizing an updating format for the signal or packet carrying out the updating, said format comprising the specific identifier of the memory location to be updated, the content with which said memory location is to be updated, and a resident updating count of the updating source, said count comprising a number indicative of the position of the updating message in the sequence of occasions on which the updating source has been updated inclusive of the current updating; (ii) storing for each receiving memory location the updating count of the previously received updating; (iii) comparing the updating count presently resident at the receiving memory location with the updating count of any currently received updating signal or packet; and (iv) indicating a contention situation if the compared updating counts are the same. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A computer program stored in a computer readable media, the computer program including executable computer program instructions and adapted for execution by at least one computer to modify the operation of the at least one computer;
- the modification of operation including performing a method of detecting contention in addressed memory updating in which a memory location having a specific location identifier can be updated substantially simultaneously from a plurality of sources, said method comprising the steps of;
(i) utilizing an updating format for the signal or packet carrying out the updating, said format comprising the specific identifier of the memory location to be updated, the content with which said memory location is to be updated, and a resident updating count of the updating source, said count comprising a number indicative of the position of the updating message in the sequence of occasions on which the updating source has been updated inclusive of the current updating; (ii) storing for each receiving memory location the updating count of the previously received updating; (iii) comparing the updating count presently resident at the receiving memory location with the updating count of any currently received updating signal or packet; and (iv) indicating a contention situation if the compared updating counts are the same.
- the modification of operation including performing a method of detecting contention in addressed memory updating in which a memory location having a specific location identifier can be updated substantially simultaneously from a plurality of sources, said method comprising the steps of;
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8. A system for detecting contention in addressed memory updating, said system comprising at least one memory location having a specific location identifier;
- a plurality of sources each of which can update said memory location(s) and each of which utilizes an updating format for the signal or packet carrying out the updating, said format comprising the specific identifier of the memory location to be updated, the content with which said memory location is to be updated, and a resident updating count of the updating source, said count comprising a number indicative of the position of the updating message in the sequence of occasions on which the updating source has been updated inclusive of the current updating;
a storage means associated with each said memory location and in which the updating count of the previously received updating is stored;
comparison means to compare the previously stored updating count with the updating count of any currently received updating signal or packet; and
contention indicating means connected with said comparison means and operable to indicate a contention situation if the compared updating counts are the same. - View Dependent Claims (9, 10, 11, 12, 13)
- a plurality of sources each of which can update said memory location(s) and each of which utilizes an updating format for the signal or packet carrying out the updating, said format comprising the specific identifier of the memory location to be updated, the content with which said memory location is to be updated, and a resident updating count of the updating source, said count comprising a number indicative of the position of the updating message in the sequence of occasions on which the updating source has been updated inclusive of the current updating;
Specification