Bug 2068120

The Transparent Huge Pages (THP) feature of RHEL can have severe negative impacts on memory consumption and performance for RHDS 11. Furthermore, THP related issues can be very hard to troubleshoot and root cause, leading to high support and customer costs. The following text (or a better written equivalent) should be added to RHDS 11 and later install/deploy guide (as appropriate) : 


"Transparent Huge Pages (THP) Linux memory management feature is enabled by default on RHEL. While it does benefit some workloads in terms of performnace gains, it has been found to be counter productive when used with RHDS and the JEMALLOC memory allocator that ships with it.

THP works best with large, contigious allocation patterns but can actually degrade the performance for small, sparse allocation patterns, that are typical to RHDS with its sparse, database like workloads, and lead to a significant memory growth and overhead, where the RHDS server process resident memory size might eventually exceed the limit and get terminated by the OOM killer as the worst case scenario. 

This is due to increased memory fragmentation, memory pressure, and additional work required by the kernel to coalesce and maintain THP for RHDS server process sparse memory allocation patterns.

To avoid these performance and memory consumption issues it is therefore recommended to disable the THP on any systems where RHDS is installed. Please refer to the following RHEL documentation for further details

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/performance_tuning_guide/sect-red_hat_enterprise_linux-performance_tuning_guide-configuring_transparent_huge_pages

https://access.redhat.com/solutions/3799821"