CHOOM(1) User Commands CHOOM(1)
choom - display and adjust OOM-killer score. choom -p PID choom -p PID -n number choom -n number [--] command [argument ...]
The choom command displays and adjusts Out-Of-Memory killer score setting.
-p, --pid pid Specifies process ID. -n, --adjust value Specify the adjust score value. -h, --help Display help text and exit. -V, --version Display version information and exit.
Linux kernel uses the badness heuristic to select which process gets killed in out of memory conditions. The badness heuristic assigns a value to each candidate task ranging from 0 (never kill) to 1000 (always kill) to determine which process is targeted. The units are roughly a proportion along that range of allowed memory the process may allocate from based on an estimation of its current memory and swap use. For example, if a task is using all allowed memory, its badness score will be 1000. If it is using half of its allowed memory, its score will be 500. There is an additional factor included in the badness score: the current memory and swap usage is discounted by 3% for root processes. The amount of "allowed" memory depends on the context in which the oom killer was called. If it is due to the memory assigned to the allocating task’s cpuset being exhausted, the allowed memory represents the set of mems assigned to that cpuset. If it is due to a mempolicy’s node(s) being exhausted, the allowed memory represents the set of mempolicy nodes. If it is due to a memory limit (or swap limit) being reached, the allowed memory is that configured limit. Finally, if it is due to the entire system being out of memory, the allowed memory represents all allocatable resources. The adjust score value is added to the badness score before it is used to determine which task to kill. Acceptable values range from -1000 to +1000. This allows userspace to polarize the preference for oom killing either by always preferring a certain task or completely disabling it. The lowest possible value, -1000, is equivalent to disabling oom killing entirely for that task since it will always report a badness score of 0. Setting an adjust score value of +500, for example, is roughly equivalent to allowing the remainder of tasks sharing the same system, cpuset, mempolicy, or memory controller resources to use at least 50% more memory. A value of -500, on the other hand, would be roughly equivalent to discounting 50% of the task’s allowed memory from being considered as scoring against the task.
Karel Zak <firstname.lastname@example.org>
For bug reports, use the issue tracker at https://github.com/karelzak/util-linux/issues.
The choom command is part of the util-linux package which can be downloaded from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>. This page is part of the util-linux (a random collection of Linux utilities) project. Information about the project can be found at ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have a bug report for this manual page, send it to email@example.com. This page was obtained from the project's upstream Git repository ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on 2021-08-27. (At that time, the date of the most recent commit that was found in the repository was 2021-08-24.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which is not part of the original manual page), send a mail to firstname.lastname@example.org util-linux 2.37.85-637cc 2021-04-02 CHOOM(1)
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