PostgreSQL 12 High Availability Cookbook - Third Edition

Be wary of THP

Addressing memory efficiently is sometimes very difficult, especially on large servers equipped with vast amounts of RAM. For the sake of efficiency, more modern Linux kernels might attempt to communicate with larger preallocated blocks of memory.

Normally, this would be extremely beneficial. However, handling such large contiguous memory segments requires regular maintenance procedures that can disrupt processes assigned to that portion of RAM. In the wrong circumstances, PostgreSQL services may be implicitly suspended for tens of seconds while memory is defragmented.

Due to this, we strongly recommend disabling these if possible. This can be done with the following commands:

echo never > /sys/kernel/mm/transparent_hugepage/enabled ...