Configuring deferred writing and ultra-large memory
Transparent Huge Pages (THP) is a Linux® memory management system that reduces the overhead of Translation Lookaside Buffer (TLB) lookups on machines with large amounts of memory by using larger memory pages.
Ultra-large main memory configurations and deferred writing are configured in the user interface in . If you are using it on Linux operating systems, you might experience faster restarts and more stable latencies when transparent huge pages are disabled. Transparent huge pages might block the memory for seconds when it is defragmenting the RAM. During defragmentation, it is not possible to make even small memory allocations.
Be careful with this setting. It can also result in slower overall message computation when deferred writing is disabled.
To disable transparent huge pages temporarily, run the following command:
echo never > /sys/kernel/mm/transparent_hugepage/defrag
echo never > /sys/kernel/mm/transparent_hugepage/enabledNext, restart IBM® Safer Payments. To check whether transparent huge pages are disabled, run the following command:
cat /sys/kernel/mm/transparent_hugepage/enabledThe output is:
always madvise [never]In RHEL, you can disable transparent huge pages with the command tuned.
See https://access.redhat.com/solutions/1320153 for details.
You can query the current active profile with:
# tuned-adm active
Current active profile: latency-performanceTo create a customized profile, create a new directory in the /etc/tuned directory with the wanted profile name.
# mkdir /etc/tuned/myprofile-nothpmyprofile-nothp,
and insert the new tuning information.
# cat /etc/tuned/myprofile-nothp/tuned.conf
[main]
include= latency-performance
[vm]
transparent_hugepages=neverNext, make the script executable:
# chmod +x /etc/tuned/myprofile-nothp/tuned.confNext, enable myprofile:
# tuned-adm profile myprofile-nothp