[gclist] Fragmentation terminology
Thu, 15 May 1997 14:38:04 +0100
> || Fragmentation is when an allocator cannot satisfy a request [without
> || going to the OS for more memory] despite there being sufficient unused
> || space.
> Picking nits (since you are discussing terminology): in OS circles,
> we call fragmentation the fact that there are unused/unusable holes
> in the memory allocation. So there are degrees of fragmentation;
> e.g. it makes sense to say "a bit of fragmentation doesn't hurt",
> "this disk is severely fragmented". Under your definition these
> sentences would not make sense.
Yes, of course, my definition above is sloppy. Of course a finished
definition must allow for these uses. There are problems with using a
single number to describe fragmentation (which is fundamentally a
multi-dimensional effect) and therefore with saying "a lot of
fragmentation", but one can get away with it in most circumstances.