[0xbear]

And 99% of developers spend their entire careers without giving as much as a passing thought to cache locality. Quick, how long, in cycles, does it take to retrieve data from RAM? About 200 cycles. 200 cycles is a very long time if you miss cache often. Scattered RAM reads can be _slower_ than sustained linear disk reads (that is, once the disk actually gets around to reading, which takes a while).

[flukus]

90% of developers are working in languages where you can't really do much about cache misses, or doing so will at least involve some very non-idiomatic code. If you can't do much about the problem it's not really helpful to be thinking about it much.

[0xbear]

I don't disagree. And for 90% of them worrying about cache locality or branch mispredictions on a daily basis would be a waste of time. It's fine to deliberately ignore such concerns. It's somewhat less fine to know absolutely nothing about how programs are actually executed, and what makes them go fast.

[lathiat]

It's even worse when you get into interpreted languages like Python and Ruby. Bad efficiency at that level which translates to dreadful if not totally broken efficiency at the cache level.

[bitL]

Bbbut JIT compiler solves everything, right?

BTW, this is a blind spot/elephant in the room of most *VM-based and functional languages nobody wants to talk about...