My databases professor at my university once brought up Jim Gray's data latency analogy to illustrate the costs of using different types of storage. Basically it goes something like this:
Using a register is like interacting with information in your own brain, using an L1 cache is like walking to a bookshelf in the room you're in, using an L2 cache is like walking across campus, using RAM is like going to Sacramento (we were in Berkeley), hitting the disk is like going to Pluto, and using tape drives is like going to Andromeda.
I never fully registered the consequences of hitting disk until then.
My company does this, but in reverse, whenever someone is getting something to eat there's a metaphor for it. Cache means you've already got it, hitting memory means you need to go to the kitchen, disk means you need a trip to the store, regisers of course means you're actively chewing.
I really like this analogy. When the article said "Numbers everyone should know", it's not really the numbers that matter, but the general relative scale of performance costs for common operations. IOTW, memorizing the nanoseconds of a cache hit isn't useful, but knowing how many times slower disk is than ram is.
Using a register is like interacting with information in your own brain, using an L1 cache is like walking to a bookshelf in the room you're in, using an L2 cache is like walking across campus, using RAM is like going to Sacramento (we were in Berkeley), hitting the disk is like going to Pluto, and using tape drives is like going to Andromeda.
I never fully registered the consequences of hitting disk until then.