Merge pull request #80236 from ShaunaDiaz/OSDOCS-11444

OSDOCS-11444: Adds low latency to MicroShift

Author: ShaunaDiaz

_attributes/attributes-microshift.adoc

@@ -18,6 +18,8 @@
 :op-system-base: RHEL
 :op-system-ostree-first: Red Hat Enterprise Linux for Edge (RHEL for Edge)
 :op-system-ostree: RHEL for Edge
+:op-system-rt-kernel: Red Hat Enterprise Linux for Real Time (real-time kernel)
+:op-system-rtk: real-time kernel
 :op-system-version: 9.4
 :op-system-version-major: 9
 :op-system-bundle: Red Hat Device Edge

_topic_maps/_topic_map_ms.yml

@@ -397,8 +397,13 @@ Topics:
   File: microshift-greenboot-checking-status
 - Name: Configuring audit logging policies
   File: microshift-audit-logs-config
-- Name: Workload partitioning
-  File: microshift-workload-partitioning
+- Name: Configuring low latency
+  Dir: microshift_low_latency
+  Topics:
+  - Name: Configuring low latency
+    File: microshift-low-latency
+  - Name: Workload partitioning
+    File: microshift-workload-partitioning
 ---
 Name: Networking
 Dir: microshift_networking

microshift_configuring/microshift_low_latency/_attributes

@@ -0,0 +1 @@
+../../_attributes/

microshift_configuring/microshift_low_latency/images

@@ -0,0 +1 @@
+../../images/

microshift_configuring/microshift_low_latency/microshift-low-latency.adoc

@@ -0,0 +1,98 @@
+:_mod-docs-content-type: ASSEMBLY
+[id="microshift-low-latency"]
+= Configuring low latency
+include::_attributes/attributes-microshift.adoc[]
+:context: microshift-low-latency
+
+toc::[]
+
+You can configure and tune low latency capabilities to improve application performance on edge devices.
+
+include::modules/microshift-low-latency-concept.adoc[leveloffset=+1]
+
+//additional resources for the low latency concept
+[role="_additional-resources"]
+.Additional resources
+* link:https://docs.redhat.com/en/documentation/openshift_container_platform/4.16/html/scalability_and_performance/low-latency-tuning#cnf-understanding-low-latency_cnf-understanding-low-latency[About low latency] (OpenShift Container Platform documentation)
+
+include::modules/microshift-install-rpms-low-latency.adoc[leveloffset=+1]
+
+include::modules/microshift-low-latency-config-yaml.adoc[leveloffset=+1]
+
+//additional resources for the config.yaml
+[role="_additional-resources"]
+.Additional resources
+//TODO * workload partitioning crossref here
+* xref:../../microshift_configuring/microshift-using-config-tools.adoc#microshift-config-yaml_microshift-configuring[Using a YAML configuration file]
+* link:https://kubernetes.io/docs/reference/config-api/kubelet-config.v1beta1/#kubelet-config-k8s-io-v1beta1-KubeletConfiguration[KubeletConfiguration reference] (Kubernetes upstream documentation)
+
+//RHEL TuneD
+include::modules/microshift-low-latency-tuned-conc.adoc[leveloffset=+1]
+
+//microshift-baseline is the name of the profile and used for automatic activation settings
+//microshift-baseline-variables.conf is the file for user tweaks
+include::modules/microshift-low-latency-tuned-profile.adoc[leveloffset=+2]
+
+//additional resources for tuned profiles
+[role="_additional-resources"]
+[id="additional-resources-tuned-profile_{context}"]
+.Additional resources
+* link:https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/monitoring_and_managing_system_status_and_performance/getting-started-with-tuned_monitoring-and-managing-system-status-and-performance[Getting started with TuneD] (RHEL documentation)
+* link:https://www.redhat.com/sysadmin/linux-tuned-tuning-profiles[How to manage tuning profiles in Linux] (Red Hat blog)
+
+//microshift-baseline is the name of the profile and used for automatic activation settings
+include::modules/microshift-low-latency-tuned-auto.adoc[leveloffset=+2]
+
+//additional resources for tuned profiles automatic activation
+[role="_additional-resources"]
+[id="additional-resources-tuned-auto_{context}"]
+.Additional resources
+* xref:../../microshift_install/microshift-greenboot.adoc#greenboot-directories-details_microshift-greenboot[Greenboot directories details]
+
+//RHEL real-time kernel
+include::modules/microshift-low-latency-kernelrt-conc.adoc[leveloffset=+1]
+
+include::modules/microshift-low-latency-install-kernelrt-rpm.adoc[leveloffset=+2]
+
+include::modules/microshift-low-latency-install-kernelrt-rhel-edge.adoc[leveloffset=+2]
+
+[id="microshift-low-latency-install-kernelrt-rhel-edge-buildimage_{context}"]
+== Building the {op-system-ostree-first} image with the real-time kernel
+
+Complete the build process by starting with the following procedure to embed {microshift-short}in a {op-system-ostree} image. Then complete the remaining steps in the installation documentation for installing {microshift-short} in a {op-system-ostree} image:
+
+* xref:../../microshift_install/microshift-embed-in-rpm-ostree.adoc#microshift-creating-ostree-iso_microshift-embed-in-rpm-ostree[Embedding in a {op-system-ostree} image]
+
+//additional resources for real-time kernel
+[role="_additional-resources"]
+[id="additional-resources-rtk_{context}"]
+.Additional resources
+* link:https://docs.redhat.com/en/documentation/red_hat_enterprise_linux_for_real_time/9[Red Hat Enterprise Linux for Real Time 9] (RHEL documentation)
+* link:https://osbuild.org/docs/on-premises/installation/managing-repositories/#using-repositories-that-require-subscription[Using repositories that require subscription] (osbuild documentation)
+* link:https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/composing_a_customized_rhel_system_image/creating-system-images-with-composer-command-line-interface_composing-a-customized-rhel-system-image#building-rhel-images-by-using-the-real-time-kernel_creating-system-images-with-composer-command-line-interface[Building RHEL images by using the real-time kernel] for more information.
+* link:https://docs.redhat.com/en/documentation/red_hat_enterprise_linux_for_real_time/9/html/installing_rhel_9_for_real_time/assembly_installing-rhel-for-real-time_installing-rhel-9-for-real-time#post-installation-instructions_assembly_installing-rhel-for-real-time[Post installation instructions] (RHEL for Real Time documentation)
+* xref:../../microshift_install/microshift-embed-in-rpm-ostree.adoc#microshift-embed-in-rpm-ostree[Embedding in a {op-system-ostree} image]
+
+* link:https://access.redhat.com/solutions/4096521[FAQ about RHEL for Real Time (kernel-rt)]
+//Can likely remove KCS after 2024 as it may go out of date
+
+include::modules/microshift-low-latency-prepare-workload.adoc[leveloffset=+1]
+
+//additional resources for preparing the workload
+[role="_additional-resources"]
+[id="additional-resources-prep-workload_{context}"]
+.Additional resources
+
+* link:https://docs.openshift.com/container-platform/4.16/scalability_and_performance/low_latency_tuning/cnf-provisioning-low-latency-workloads.html#cnf-configuring-high-priority-workload-pods_cnf-provisioning-low-latency[Disabling power saving mode for high priority pods] (Red Hat OpenShift Container Platform documentation)
+
+* link:https://docs.openshift.com/container-platform/4.16/scalability_and_performance/low_latency_tuning/cnf-provisioning-low-latency-workloads.html#cnf-disabling-cpu-cfs-quota_cnf-provisioning-low-latency[Disabling CPU CFS quota] (Red Hat OpenShift Container Platform documentation)
+
+* link:https://docs.openshift.com/container-platform/4.16/scalability_and_performance/low_latency_tuning/cnf-provisioning-low-latency-workloads.html#cnf-disabling-interrupt-processing-for-individual-pods_cnf-provisioning-low-latency[Disabling interrupt processing for CPUs where pinned containers are running] (Red Hat OpenShift Container Platform documentation)
+
+include::modules/microshift-low-latency-rhel-edge-blueprint-rtk.adoc[leveloffset=+1]
+
+//additional resources for workload partitioning
+[role="_additional-resources"]
+[id="additional-resources-wp_{context}"]
+.Additional resources
+* xref:../microshift_low_latency/microshift-workload-partitioning.adoc#microshift-workload-partitioning[Workload partitioning]

microshift_configuring/microshift-workload-partitioning.adoc renamed to microshift_configuring/microshift_low_latency/microshift-workload-partitioning.adoc

@@ -0,0 +1 @@
+../../modules/

microshift_configuring/microshift_low_latency/modules

@@ -0,0 +1 @@
+../../snippets/

microshift_configuring/microshift_low_latency/snippets

@@ -6,17 +6,21 @@
 [id="microshift-config-yaml_{context}"]
 = Using a YAML configuration file
 
-At start up, {microshift-short} checks the system-wide `/etc/microshift/` directory for a configuration file named `config.yaml`. If the configuration file does not exist in the directory, the built-in default values are used to start the service.
+At start up, {microshift-short} checks the system-wide `/etc/microshift/` directory for a configuration file named `config.yaml`. If the configuration file does not exist in the directory, built-in default values are used to start the service.
 
 [id="microshift-yaml-custom_{context}"]
 == Custom settings
-To create custom configurations, you must create a `config.yaml` file in the `/etc/microshift/` directory, and then change any settings that are expected to override the defaults before starting or restarting {microshift-short}.
+To create custom configurations, make a copy of the provided `config.yaml.default` file that is provided in the `/etc/microshift/` directory, renaming it `config.yaml`. Keep this file in the `/etc/microshift/` directory, and then you can change supported settings that are expected to override the defaults before starting or restarting {microshift-short}.
 
 [IMPORTANT]
 ====
 Restart {microshift-short} after changing any configuration settings to have them take effect. The `config.yaml` file is read only when {microshift-short} starts.
 ====
 
+[id="microshift-yaml-custom-settings_{context}"]
+== Separate restarts
+Applications and other optional services used with your {microshift-short} cluster might also need to be restarted separately to apply configuration changes throughout the cluster. For example, when making changes to certain networking settings, you must stop and restart service and application pods to apply those changes. See each procedure for the task you are completing for more information.
+
 [TIP]
 ====
 If you add all of the configurations you need at the same time, you can minimize system restarts.

modules/microshift-config-yaml.adoc

@@ -0,0 +1,35 @@
+// Module included in the following assemblies:
+//
+// microshift_configuring/microshift_low_latency/microshift-low-latency.adoc
+
+:_mod-docs-content-type: PROCEDURE
+[id="microshift-installing-low-latency-rpm-package_{context}"]
+= Installing the {microshift-short} low latency RPM package
+
+When you install {microshift-short}, the low latency RPM package is not installed by default. You can install the low latency RPM as an optional package.
+
+.Prerequisites
+
+. You installed the {microshift-short} RPM.
+. You configured workload partitioning for {microshift-short}.
+
+.Procedure
+
+* Install the low latency RPM package by running the following command:
++
+[source,terminal]
+----
+$ sudo dnf install -y microshift-low-latency
+----
++
+[TIP]
+====
+Wait to restart the host until after activating your TuneD profile. Restarting the host restarts {microshift-short} and CRI-O, which applies the low latency manifests and activates the TuneD profile.
+====
+
+.Next steps
+. Configure the kubelet parameter for low latency in the {microshift-short} `config.yaml`.
+. Tune your operating system, for example, configure and activate a TuneD profile.
+. Optional: Configure automatic activation of your TuneD profile.
+. Optional: If you are using the x86_64 architecture, install {op-system-rt-kernel}.
+. Prepare your workloads for low latency.