Add docs on transparent huge pages (THP) setting (#19343)

* Add docs on transparent huge pages (THP) setting

Fixes DOC-12097

Author: rmloveland

src/current/v23.1/recommended-production-settings.md

@@ -22,6 +22,12 @@ For optimal cluster performance, Cockroach Labs recommends that all nodes use th
 
 We recommend running a [glibc](https://www.gnu.org/software/libc/)-based Linux distribution and Linux kernel version from the last 5 years, such as [Ubuntu](https://ubuntu.com/), [Red Hat Enterprise Linux (RHEL)](https://www.redhat.com/technologies/linux-platforms/enterprise-linux), [CentOS](https://www.centos.org/), or [Container-Optimized OS](https://cloud.google.com/container-optimized-os/docs).
 
+We have observed increased memory usage in rare cases due to [transparent huge pages (THP)](https://www.kernel.org/doc/html/latest/admin-guide/mm/transhuge.html) being enabled (i.e., set to `always`). New deployments should configure THP with the `madvise` option.
+
+Existing deployments that have THP enabled using the `always` option should change it to `madvise` unless they are currently running with a comfortable memory usage margin.
+
+The method for permanently changing the THP setting across reboots depends on the operating system. For Red Hat Enterprise Linux, refer to the [Red Hat documentation](https://access.redhat.com/solutions/46111).
+
 ## Hardware
 
 {% include {{ page.version.version }}/prod-deployment/terminology-vcpu.md %}

src/current/v23.2/recommended-production-settings.md

@@ -22,6 +22,12 @@ For optimal cluster performance, Cockroach Labs recommends that all nodes use th
 
 We recommend running a [glibc](https://www.gnu.org/software/libc/)-based Linux distribution and Linux kernel version from the last 5 years, such as [Ubuntu](https://ubuntu.com/), [Red Hat Enterprise Linux (RHEL)](https://www.redhat.com/technologies/linux-platforms/enterprise-linux), [CentOS](https://www.centos.org/), or [Container-Optimized OS](https://cloud.google.com/container-optimized-os/docs).
 
+We have observed increased memory usage in rare cases due to [transparent huge pages (THP)](https://www.kernel.org/doc/html/latest/admin-guide/mm/transhuge.html) being enabled (i.e., set to `always`). New deployments should configure THP with the `madvise` option.
+
+Existing deployments that have THP enabled using the `always` option should change it to `madvise` unless they are currently running with a comfortable memory usage margin.
+
+The method for permanently changing the THP setting across reboots depends on the operating system. For Red Hat Enterprise Linux, refer to the [Red Hat documentation](https://access.redhat.com/solutions/46111).
+
 ## Hardware
 
 {% include {{ page.version.version }}/prod-deployment/terminology-vcpu.md %}

src/current/v24.1/recommended-production-settings.md

@@ -22,6 +22,12 @@ For optimal cluster performance, Cockroach Labs recommends that all nodes use th
 
 We recommend running a [glibc](https://www.gnu.org/software/libc/)-based Linux distribution and Linux kernel version from the last 5 years, such as [Ubuntu](https://ubuntu.com/), [Red Hat Enterprise Linux (RHEL)](https://www.redhat.com/technologies/linux-platforms/enterprise-linux), [CentOS](https://www.centos.org/), or [Container-Optimized OS](https://cloud.google.com/container-optimized-os/docs).
 
+We have observed increased memory usage in rare cases due to [transparent huge pages (THP)](https://www.kernel.org/doc/html/latest/admin-guide/mm/transhuge.html) being enabled (i.e., set to `always`). New deployments should configure THP with the `madvise` option.
+
+Existing deployments that have THP enabled using the `always` option should change it to `madvise` unless they are currently running with a comfortable memory usage margin.
+
+The method for permanently changing the THP setting across reboots depends on the operating system. For Red Hat Enterprise Linux, refer to the [Red Hat documentation](https://access.redhat.com/solutions/46111).
+
 ## Hardware
 
 {% include {{ page.version.version }}/prod-deployment/terminology-vcpu.md %}

src/current/v24.2/recommended-production-settings.md

@@ -22,6 +22,12 @@ For optimal cluster performance, Cockroach Labs recommends that all nodes use th
 
 We recommend running a [glibc](https://www.gnu.org/software/libc/)-based Linux distribution and Linux kernel version from the last 5 years, such as [Ubuntu](https://ubuntu.com/), [Red Hat Enterprise Linux (RHEL)](https://www.redhat.com/technologies/linux-platforms/enterprise-linux), [CentOS](https://www.centos.org/), or [Container-Optimized OS](https://cloud.google.com/container-optimized-os/docs).
 
+We have observed increased memory usage in rare cases due to [transparent huge pages (THP)](https://www.kernel.org/doc/html/latest/admin-guide/mm/transhuge.html) being enabled (i.e., set to `always`). New deployments should configure THP with the `madvise` option.
+
+Existing deployments that have THP enabled using the `always` option should change it to `madvise` unless they are currently running with a comfortable memory usage margin.
+
+The method for permanently changing the THP setting across reboots depends on the operating system. For Red Hat Enterprise Linux, refer to the [Red Hat documentation](https://access.redhat.com/solutions/46111).
+
 ## Hardware
 
 {% include {{ page.version.version }}/prod-deployment/terminology-vcpu.md %}

src/current/v24.3/recommended-production-settings.md

@@ -22,6 +22,12 @@ For optimal cluster performance, Cockroach Labs recommends that all nodes use th
 
 We recommend running a [glibc](https://www.gnu.org/software/libc/)-based Linux distribution and Linux kernel version from the last 5 years, such as [Ubuntu](https://ubuntu.com/), [Red Hat Enterprise Linux (RHEL)](https://www.redhat.com/technologies/linux-platforms/enterprise-linux), [CentOS](https://www.centos.org/), or [Container-Optimized OS](https://cloud.google.com/container-optimized-os/docs).
 
+We have observed increased memory usage in rare cases due to [transparent huge pages (THP)](https://www.kernel.org/doc/html/latest/admin-guide/mm/transhuge.html) being enabled (i.e., set to `always`). New deployments should configure THP with the `madvise` option.
+
+Existing deployments that have THP enabled using the `always` option should change it to `madvise` unless they are currently running with a comfortable memory usage margin.
+
+The method for permanently changing the THP setting across reboots depends on the operating system. For Red Hat Enterprise Linux, refer to the [Red Hat documentation](https://access.redhat.com/solutions/46111).
+
 ## Hardware
 
 {% include {{ page.version.version }}/prod-deployment/terminology-vcpu.md %}

src/current/v25.1/recommended-production-settings.md

@@ -22,6 +22,12 @@ For optimal cluster performance, Cockroach Labs recommends that all nodes use th
 
 We recommend running a [glibc](https://www.gnu.org/software/libc/)-based Linux distribution and Linux kernel version from the last 5 years, such as [Ubuntu](https://ubuntu.com/), [Red Hat Enterprise Linux (RHEL)](https://www.redhat.com/technologies/linux-platforms/enterprise-linux), [CentOS](https://www.centos.org/), or [Container-Optimized OS](https://cloud.google.com/container-optimized-os/docs).
 
+We have observed increased memory usage in rare cases due to [transparent huge pages (THP)](https://www.kernel.org/doc/html/latest/admin-guide/mm/transhuge.html) being enabled (i.e., set to `always`). New deployments should configure THP with the `madvise` option.
+
+Existing deployments that have THP enabled using the `always` option should change it to `madvise` unless they are currently running with a comfortable memory usage margin.
+
+The method for permanently changing the THP setting across reboots depends on the operating system. For Red Hat Enterprise Linux, refer to the [Red Hat documentation](https://access.redhat.com/solutions/46111).
+
 ## Hardware
 
 {% include {{ page.version.version }}/prod-deployment/terminology-vcpu.md %}