question: should_compact_retry limit

From: Mike Kravetz
Date: Tue Jun 04 2019 - 19:35:02 EST

While looking at some really long hugetlb page allocation times, I noticed
instances where should_compact_retry() was returning true more often that
I expected. In one allocation attempt, it returned true 765668 times in a
row. To me, this was unexpected because of the following:

int max_retries = MAX_COMPACT_RETRIES;

However, if should_compact_retry() returns true via the following path we
do not increase the retry count.

* make sure the compaction wasn't deferred or didn't bail out early
* due to locks contention before we declare that we should give up.
* But do not retry if the given zonelist is not suitable for
* compaction.
if (compaction_withdrawn(compact_result)) {
ret = compaction_zonelist_suitable(ac, order, alloc_flags);
goto out;

Just curious, is this intentional?
Mike Kravetz