OOM score
also: OOM killer score, oom_score
A numerical value assigned by the Linux kernel that determines the priority of a process to be killed when the system runs out of memory (OOM Kill).
When available system memory becomes critically low, the Linux kernel's Out-Of-Memory (OOM) killer selects processes to terminate. The OOM score is a number between 0 and 1000+ that ranks each process by its likelihood of being killed—higher scores are killed first.
The kernel calculates OOM score based on memory usage and the OOM score adjust parameter. A process using 100 MB of memory on a 1 GB system has a higher base score than one using 10 MB. You can view and adjust these values in /proc/[PID]/oom_score and /proc/[PID]/oom_score_adj.
For example, a memory-hungry database might have an OOM score of 850, while a critical system service with oom_score_adj = -1000 becomes unkillable. Adjusting oom_score_adj to -500 reduces a process's kill priority, useful for protecting important applications.