Fragmentation was RE: [GD-General] Compile times

[Brian H. <bri...@py...>]

> Virtual memory hides a multitude of sins.
> 
> Fragmentation being the big one.

Unfortunately, no it doesn't.  Because the problem isn't fragmentation
of physical memory, it's fragmentation of virtual addresses.

There's a common misconception that you get 32-bits of address space on,
say, Windows.  You don't.  You get 31-bits, since half the address space
is reserved for the OS.  Out of this 2GB you have to share between heap,
static data, and code.  So realistically speaking, you have a little
less than 2GB.

If you allocate and delete large chunks of memory, interspersed with
small ones, you will fragment that address space such that you may have
enough physical memory for an operation, but you won't have enough
contiguous address space to allocate it.

Brian