The costs of the i386 to x86-64 upgrade

If you read my previous article onDOS memory models, you may have dismissed everything I wrote as legacy cruft from the 1990s that nobody cares about any longer". After all, computers have evolved from sporting 8-bit processors to 64-bit processors and, on the way, the amount of memory that these computers can leverage has grown orders of magnitude: the 8086, a 16-bit machine with a 20-bit address space, could only use 1MB of memory while today's 64-bit machines can theoretically access 16EB.

All of this growth has been in service of ever-growing programs. But... even if programs are now more sophisticated than they were before, do they allreallyrequire access to a 64-bit address space? Has the growth from 8 to 64 bits been a net positive in performance terms?

Let's try to answer those questions to find some very surprising answers. But first, some theory.

Julio Merino

It's not quite weekend yet, but I'm still calling this some light reading for the weekend.