Deadlock avoidance for systolic communication

The nature of the deadlock problem for the systolic model of communication is described. This problem does not exist for special-purpose systolic arrays for which the hardware designer can afford providing as many queues as required by the specific computation that the array intends to implement. However, for programmable systolic arrays, the number of messages crossing the interval between two adjacent cells can be arbitrarily large, depending on the program. As a result, the possibility of deadlock always exists, since the number of queues between adjacent cells is fixed. The problem of avoiding queue-induced deadlocks, for deadlock-free programs, at run time is described, and a solution to the problem is given. Schemes for consistent labeling and compatible queue assignment, for which the solution calls, as also described, as is how to take advantage of the buffering capability provided by queues.<
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