## Userspace Out-Of-Memory (OOM) killer for linux systems. Out of memory killing has historically happened inside kernel space. On a memory overcommitted linux system, malloc(2) and friends usually never fail. However, if an application dereferences the returned pointer and the system has run out of physical memory, the linux kernel is forced take extreme measures, up to and including killing processes. This is sometimes a slow and painful process because the kernel can spend an unbounded amount of time swapping in and out pages and evicting the page cache. Furthermore, configuring policy is not very flexible while being somewhat complicated. oomd aims to solve this problem in userspace. oomd leverages PSI and cgroupv2 to monitor a system holistically. oomd then takes corrective action in userspace before an OOM occurs in kernel space. Corrective action is configured via a flexible plugin system, in which custom code can be written. By default, this involves killing offending processes. This enables an unparalleled level of flexibility where each workload can have custom protection rules. Furthermore, time spent livedlocked in kernelspace is minimized.

This is a companion discussion topic for the original entry at
  1. They kill all the session instead of one process.
  2. They uses 7% CPU on my VM.
  3. I turned off the swap and started opening browser tabs, and in the end the system freezed.

Resume: they are not for desktop. Don’t advise it to use on desktop. Use earlyoom or nohang on desktop instead of oomd.