Hot spot
1. (primarily used by
C/
Unix programmers, but spreading) It is received wisdom that in most programs, less than 10% of the code eats 90% of the execution time; if one were to graph instruction visits versus code addresses, one would typically see a few huge spikes amidst a lot of low-level noise.
Such spikes are called "hot spots" and are good candidates for heavy optimisation or
hand-hacking.
The term is especially used of tight loops and recursions in the code's central algorithm, as opposed to (say) initial set-up costs or large but infrequent I/O operations.
See
tune,
bum,
hand-hacking.
2. The active location of a cursor on a bit-map display.
"Put the mouse's hot spot on the "ON" widget and click the left button."
3. A screen region that is sensitive to mouse clicks, which trigger some action.
Hypertext help screens are an example, in which a hot spot exists in the vicinity of any word for which additional material is available.
4. In a massively parallel computer with
shared memory, the one location that all 10,000 processors are trying to read or write at once (perhaps because they are all doing a
busy-wait on the same lock).
5. More generally, any place in a hardware design that turns into a performance bottleneck due to resource contention.
[
Jargon File]
