2 ms·

A couple of dumb questions: 1) In practice, how much of low level optimization is writing code differently, vs compiler tweaking? How much is done by offloadin

A couple of dumb questions: 1) In practice, how much of low level optimization is writing code differently, vs compiler tweaking? How much is done by offloading to other (specialized) hardware? 2) How could someone learn to do something like this. I’ve never had any situations where micro optimization is necessary or even useful. Never had to work with extremely large amounts of data, worry about tight timing of concerns, etc. and it seems like outside of an industrial setting it seems like getting access to the types of problems requiring this is the most difficult part. I mean, I suppose simply doing sorts on massive quantities of numbers is one thing, but it feels limited.

ncmncm 5y ago
All those things are done, mostly at different times by different people. Optimizations are very slow to move into compilers, but once there improve potentially millions of programs, so there is a lot of value in it. But there is practically no value to be extracted from a better compiler, so the money to pay for that is very limited. Any optimization that can be pushed into a compiler can be done "by hand" instead. All are done that way at first, and just a few move into compilers, eventually, after enough people get tired of doing them by hand, or seeing them not being done by hand when they ought to be. The only way anyone learns to do it is to first need to do it. Most people don't need to, and so never do. But the highest-paying jobs are the ones that either make somebody a lot of money or save them a lot of money. The former have more upside; there is no upper limit to how much money could be made. The latter is strictly limited: you can't save anybody more money than the difference between what they are paying and what they pay you. But the latter is easier to get paid for, because people know what they are paying and hate it. Money you save them is money into their pocket over and over again. Sorting is something people write about optimizing because everybody understands what it means. Few people depend on how fast ordinary sorting is (or, anyway, know they do), but the techniques you need to make sorting fast are the same as you need to make other things fast. Studying lots of optimizations makes you better able to reason about what you can do to optimize.

ncmncm 5y ago

All those things are done, mostly at different times by different people. Optimizations are very slow to move into compilers, but once there improve potentially millions of programs, so there is a lot of value in it. But there is practically no value to be extracted from a better compiler, so the money to pay for that is very limited. Any optimization that can be pushed into a compiler can be done "by hand" instead. All are done that way at first, and just a few move into compilers, eventually, after enough people get tired of doing them by hand, or seeing them not being done by hand when they ought to be. The only way anyone learns to do it is to first need to do it. Most people don't need to, and so never do. But the highest-paying jobs are the ones that either make somebody a lot of money or save them a lot of money. The former have more upside; there is no upper limit to how much money could be made. The latter is strictly limited: you can't save anybody more money than the difference between what they are paying and what they pay you. But the latter is easier to get paid for, because people know what they are paying and hate it. Money you save them is money into their pocket over and over again. Sorting is something people write about optimizing because everybody understands what it means. Few people depend on how fast ordinary sorting is (or, anyway, know they do), but the techniques you need to make sorting fast are the same as you need to make other things fast. Studying lots of optimizations makes you better able to reason about what you can do to optimize.