erts: Make module and export table limits tunable

[naserca]

Add the +zmml and +zmel emulator flags to set the maximum number of entries in the module_code and export_list loader index tables, raising the previously hardcoded MODULE_LIMIT (64K) and EXPORT_LIMIT (512K) caps.

Expose the current limits and counts via erlang:system_info/1 with the new module_limit, module_count, export_limit and export_count keys, and document the flags and system_info keys.

Proposed here.

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CT Test Results

    3 files    136 suites   50m 58s ⏱️
1 687 tests 1 631 ✅ 56 💤 0 ❌
2 330 runs  2 256 ✅ 74 💤 0 ❌

Results for commit e4d2f99.

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[sverker]

Thank you for a comprehensive PR.

However, I think it would be more useful if system_info for module_limit and export_limit would return the actual effective limit. This is what process_limit and port_limit does, but not atom_limit.

My suggestion is to insert a new commit first that changes the behavior of atom_limit by changing erts_index_init() to set t->limit to the real limit aligned up by INDEX_PAGE_SIZE.

And then mimic erts_get_atom_limit() that returns the set limit of the underlying index table:

Uint erts_get_atom_limit(void)
{
    return erts_atom_table.limit;
}

[naserca]

Makes sense, and thanks! Do you want the atom_limit fix in a separate PR? Or just in a separate commit here in this PR?

[naserca]

Went ahead and opened #11364.

[sverker]

#11364 has been merged to master.

[naserca]

Thanks @sverker! I've updated this PR.

[sverker]

@naserca Thanks for the contribution.