Comment 9 for bug 1838575

T3: use 1.2 TB with one PT device - THP=off
  #1: 476 seconds
  #2: 31 seconds
  #3: 20 seconds

ubuntu@akis:~$ echo never | sudo tee /sys/kernel/mm/transparent_hugepage/enabled
never
ubuntu@akis:~$ cat /sys/kernel/mm/transparent_hugepage/enabled
always madvise [never]

Samples: 88K of event 'cycles:ppp', Event count (approx.): 44410625251
Overhead Shared Object Symbol
  22.12% [kernel] [k] _raw_spin_lock
  14.56% [kernel] [k] try_charge
  13.00% [kernel] [k] clear_page_erms
  11.48% [kernel] [k] get_page_from_freelist
   8.10% [kernel] [k] handle_pte_fault
   2.04% [kernel] [k] __pagevec_lru_add_fn
   1.80% [kernel] [k] follow_page_pte

We still see page scrub and mapping initialization, but no more transparent pages.
As expected this changed the perf profile but didn't provide a lot of gain
(actually a loss on init time and later on ).