hot spot
from
Jargon File (4.4.4, 14 Aug 2003)
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 {hotlink}s).
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.
from
The Free On-line Dictionary of Computing (8 July 2008)
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}]
(1995-02-16)
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