Docs Home → Develop Applications → MongoDB Manual
Disable Transparent Huge Pages (THP)
On this page
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.
However, database workloads often perform poorly with THP enabled, because they tend to have sparse rather than contiguous memory access patterns. When running MongoDB on Linux, THP should be disabled for best performance.
To ensure that THP is disabled before mongod starts,
you should create a service file for your platform's initialization
system that disables THP at boot. Instructions are provided below for
both the systemd and the System V init initialization systems.
Additionally, for RHEL / CentOS
systems that make use of ktune and tuned performance profiles,
you must create a custom tuned profile as well.
Create a Service File
To create a service file that disables THP, you will use the
built-in initialization system for your platform. Recent versions
of Linux tend to use systemd (which uses the systemctl command),
while older versions of Linux tend to use System V init (which uses
the service command). Refer to the documentation for your operating
system for more information.
Use the initialization system appropriate for your platform:
Using tuned and ktune
Important
If using tuned or ktune, you must also perform the steps in
this section after creating the service file above.
tuned and ktune are dynamic kernel tuning tools that can affect
the transparent huge pages setting on your system. If you are using
tuned / ktune on your RHEL
/ CentOS system while running mongod, you must create a custom
tuned profile to ensure that THP remains disabled.
Red Hat/CentOS 6
Create a new profile.
Create a new profile from an existing profile by copying the
relevant directory. This example uses the
virtual-guest profile as the base, and uses
virtual-guest-no-thp as the new profile:
sudo cp -r /etc/tune-profiles/virtual-guest /etc/tune-profiles/virtual-guest-no-thp
Edit ktune.sh.
Edit /etc/tune-profiles/virtual-guest-no-thp/ktune.sh
and change the set_transparent_hugepages setting to the
following:
set_transparent_hugepages never
Enable the new profile.
Enable the new profile:
sudo tuned-adm profile virtual-guest-no-thp
Red Hat/CentOS 7 and 8
Create a new profile.
Create a new directory to hold the custom tuned profile.
This example inherits from the existing virtual-guest
profile, and uses virtual-guest-no-thp as the new profile:
sudo mkdir /etc/tuned/virtual-guest-no-thp
Edit tuned.conf.
Create and edit /etc/tuned/virtual-guest-no-thp/tuned.conf so that it contains the
following:
[main] include=virtual-guest [vm] transparent_hugepages=never
This example inherits from the existing virtual-guest
profile. Select the profile most appropriate for your system.
Enable the new profile.
Enable the new profile:
sudo tuned-adm profile virtual-guest-no-thp