Improve documentation memory usage warning?

[HadrienG2]

As was pointed out multiple times before, compiling HPX has quite large memory requirements. Since improving these does not seem to be a priority at the moment, it is best to document them well.

Currently, the documentation has the following to say on the matter :

It is advisable that approximately 2 GB of memory per parallel process is available.

I can attest that this is quite accurate for the "make all" target, either in debug or release mode. However, today, when attempting a "make tests" on a debug build, I reached an new record 3 GB per parallel process. Unsurprisingly, the build crashed.

I think the documentation could warn about this better, but I am not sure how. Maybe the requirement should be turned into a lower bound, rather than an absolute number, i.e.

-approximately 2 GB of memory per parallel process
+at least 2 GB of memory per parallel process

What do you think?

[hkaiser]

We'd be happy to accept a PR to change this.

[HadrienG2]

Here's a PR for my proposal above. Again, if someone has a better idea of how to express that requirements can vary a lot depending on what is being built, I'm all ears.

[hkaiser]

This has been fixed by merging #2042