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hot spot n.
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
optimization 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, 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 gestures, which trigger some
action. World Wide Web pages now provide the canonical
examples; WWW browsers present hypertext links as hot spots which,
when clicked on, point the browser at another document (these are
specifically called hotlinks). 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.
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