The easiest way is via
$cat /sys/kernel/mm/transparent_hugepage/enabled
[always] madvise never
$ cat /sys/kernel/mm/transparent_hugepage/defrag
always defer [defer+madvise] madvise never
Julia is afaiu not very good at using madvise appropriately, and many systems default to madvise as their THP settings. The above settings respect explicit madvise, but do a pretty appropriate thing in absence of explicit user choices (which is: Use hugepages where possible, and always try to compact in a background thread).