External Fragmentation

Tags

comp-arch

Refers to a state in malloc where even though we collectively have enough unreturned memory to satisfy a request, it's split up so finely between returned blocks that there's no way to return it.

For example we could have a series of blocks 2KiB, 4KiB, 2Kib where the first and last blocks are free for allocation. If a call for 3KiB comes up we have 4KiB of free space in total but not in a series so we end up having to allocate at least 1KiB more memory for it.