Page size choice

Why are pages 4KiB anyways?

There is a trade-off between memory wasted in:

This can be seen with the extreme cases:

if the page size were 1 byte:
- granularity would be great, and the OS would never have to allocate unneeded padding memory
- but the page table would have 2^32 entries, and take up the entire memory!
if the page size were 4GiB:
- we would need to swap 4GiB to disk every time a new process becomes active
- the page size would be a single entry, so it would take almost no memory at all

x86 designers have found that 4KiB pages are a good middle ground.

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