If the memory filesystem doesn't try to decide on the order of writes to the underlying filesystem, but instead simpley creates a queue of operations and feeds them to the disk in the order they are received, then a logging filesystem can reorder and coalesce them to get the physical disk update quite quickly. A colleague did a thesis on that, and found that reordering and coalescing paid a huge benefit. Alternatively, one could have an intermediate layer which the memory filesystem could pass operations to, which could do optimizations like doing all directory operations asap and in-order and delaying all file writes until close or a certain large size had accumulated, then writing teh whole file in one fell swoop. The latter is *very* effective at increasing performancw while decreasing seeks and CPU usage. --dave
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