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Direct methods of deadlock prevention
nA protocol to prevent circular wait:
udefine
a strictly increasing linear ordering O() for resource types. Ex:
FR1:
tape drives: O(R1) = 2
FR2:
disk drives: O(R2) = 4
FR3:
printers: O(R3) = 7
uA
process initially request a number of instances of a resource type, say Ri. A
single request
must be issued to obtain several instances.
uAfter that, the process can request instances for resource type
Rj if and only if O(Rj) > O(Ri)