8.5.3.4. Understanding nodes overcommitment

To maintain optimal system performance and stability in an overcommitted environment in OpenShift Container Platform, configure your nodes to manage resource contention effectively.

When the node starts, it ensures that the kernel tunable flags for memory management are set properly. The kernel should never fail memory allocations unless it runs out of physical memory.

To ensure this behavior, OpenShift Container Platform configures the kernel to always overcommit memory by setting the vm.overcommit_memory parameter to 1, overriding the default operating system setting.

OpenShift Container Platform also configures the kernel to not panic when it runs out of memory by setting the vm.panic_on_oom parameter to 0. A setting of 0 instructs the kernel to call the OOM killer in an Out of Memory (OOM) condition, which kills processes based on priority.

You can view the current setting by running the following commands on your nodes:

$ sysctl -a |grep commit

#...
vm.overcommit_memory = 0
#...

$ sysctl -a |grep panic

#...
vm.panic_on_oom = 0
#...

You can also perform the following configurations for each node: