Control Memory Management Policies on a Node [page]deterministic

tasks

The Kubernetes *Memory Manager* enables the feature of guaranteed memory (and hugepages) allocation for pods in the `Guaranteed` [QoS class](#gloss:qos-class).

The Memory Manager employs a hint generation protocol to yield the most suitable NUMA affinity for a pod. The Memory Manager feeds the central manager (*Topology Manager*) with these affinity hints. Based on both the hints and Topology Manager policy, the pod is rejected or admitted to the node.

Moreover, the Memory Manager ensures that the memory which a pod requests is allocated from a minimum number of NUMA nodes.

For background about memory resources for Pods, read [Assign Memory Resources to Containers and Pods](/docs/tasks/configure-pod-container/assign-memory-resource/).

If you are running an older version of Kubernetes, check the documentation for the version of Kubernetes you are running.

### Resource alignment prerequisites

To align memory resources with other requested resources in a Pod spec:

the CPU Manager should be enabled and proper CPU Manager policy should be configured on a Node. See [control CPU Management Policies](/docs/tasks/administer-cluster/cpu-management-policies/);
the Topology Manager should be enabled and proper Topology Manager policy should be configured on a Node. See [control Topology Management Policies](/docs/tasks/administer-cluster/topology-manager/).

### Windows support

Windows support can be enabled via the `WindowsCPUAndMemoryAffinity` feature gate and it requires support in the container runtime. Only the [None](#policy-none) and [BestEffort](#policy-best-effort) policies are supported on Windows.

## How does the Memory Manager operate?

For Linux nodes, the Memory Manager offers the guaranteed memory (and hugepages) allocation for Pods in Guaranteed QoS class. To immediately put the Memory Manager into operation follow the guidelines in the section [Memory Manager configuration](#memory-manager-configuration), and subsequently, prepare and deploy a `Guaranteed` Pod as illustrated in the section [Placing a Pod in the Guaranteed QoS class](#placing-a-pod-in-the-guaranteed-qos-class).

The Memory Manager is a hint provider, and it provides topology hints for the Topology Manager which then aligns the requested resources according to these topology hints. On Linux, it also enforces `cgroups` (specifically, `cpuset.mems`) for Pods. The complete flow diagram concerning pod admission and deployment process is illustrated below:

![Memory Manager in the pod admission and deployment process](/images/docs/memory-manager-diagram.svg)

During this process, the Memory Manager updates its internal counters stored in [Node Map and Memory Maps][2] to manage guaranteed memory allocation.

The memory manager activates during kubelet startup if a node administrator configures `reservedMemory` for the kubelet (section [Reserved memory configuration](#reserved-memory-flag)). In this case, the kubelet updates its node map to reflect this reservation.

When the `Static` policy is configured, you must configure reserved memory for the node (for example, with the `reservedMemory` configuration field in the kubelet configuration).

An important topic in the context of Memory Manager operation is the management of NUMA groups. Each time pod's memory request is in excess of single NUMA node capacity, the Memory Manager attempts to create a group that comprises several NUMA nodes and that features extended memory capacity.

## Memory Manager configuration

Other Managers should already be configured (see [resource alignment prerequisites](#resource-alignment-prerequisites). Set the `memoryManagerPolicy` configuration field within the [kubelet configuration](), to the name of your chosen [policy](#policies).

Optionally, some amount of memory can be reserved for system or kubelet processes to increase node stability (section [Reserved memory configuration](#reserved-memory-flag)).

### Policies

Kubernetes' memory manag …(trimmed)