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11.7. Worst Fit

11.7.1. Worst Fit

A strategy contrary to best fit might make sense because it tends to minimize the effects of external fragmentation. This is called worst fit, which always allocates the largest block on the list hoping that the remainder of the block will be useful for servicing a future request. In our example, the worst fit is the block of size 45, leaving a remainder of size 15. If there are a few unusually large requests, this approach will have less chance of servicing them. If requests generally tend to be of the same size, then this might be an effective strategy. Like best fit, worst fit requires searching the entire freelist at each memory request to find the largest block. Alternatively, the freelist can be ordered from largest to smallest free block, possibly by using a priority queue implementation.

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