Preventing livelocks in processor selection of load requests
AssigneeInternational Business Machines Corporation
InventorsRichard William Doing, John R. Patty, Steven Robert Testa, Thuong Quang Truong
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Abstract
A method, and apparatus are provided for preventing livelocks in processor selection of load requests in a multiprocessor (MP) system. On random occasions a selection mechanism is changed for first holding up all requests and then a random selection is made. Then a round robin selection mechanism is used for further requests. A livelock-preventing selection mechanism includes a pair of linear feedback shift registers (LFSRs), each LFSR for generating pseudo random values.
Claims14
A method for preventing livelocks in processor selection of load requests in a multiprocessor (MP) system comprising:
- providing a pair of linear feedback shift registers (LFSRs), each LFSR generating pseudo random values;
- changing from a round-robin selection mechanism to a livelock-preventing selection mechanism and holding up all load requests on random occasions for a random number of cycles;
- making a random selection responsive to holding up all load requests;
- and
- using said round-robin selection mechanism to continue selecting load request in a round robin order following said random selection.
Apparatus for preventing livelocks in processor selection of load request in a multiprocessor (MP) system comprising:
- a pair of linear feedback shift registers (LFSRs), each LFSR generating pseudo random values;
- a round-robin selection mechanism selecting load requests in a round robin order;
- a livelock-preventing selection mechanism holding up all load requests on random occasions for a random number of cycles;
- changing from said round-robin selection mechanism to said livelock-preventing selection mechanism making a random selection responsive to holding up all load requests;
- and
- said round-robin selection mechanism selecting load requests in said round robin order following said random selection.
Dependencies are inferred from the claim text.