When does GC run?

[Kagamin]

On Tuesday, 16 October 2018 at 09:38:44 UTC, John Burton wrote:
> Is there any documentation or information about the specifics 
> of the garbage collector?
>
> The information I have found indicates that it runs to free 
> memory when the system runs out of memory to allocate. But will 
> this try to use all the system memory or some other amount 
> before trying to garbage collect? If I have a _lot_ of garbage, 
> will it try to collect that before allocating any more system 
> memory? Is this configurable in any way?

Configuration options: 
https://dlang.org/spec/garbage.html#gc_config