NAME

       choom - display and adjust OOM-killer score.

       choom -p PID

       choom -p PID -n number

       choom -n number [--] command [argument ...]

DESCRIPTION

       The choom command displays and adjusts Out-Of-Memory killer score setting.

OPTIONS

       -p, --pid pid
           Specifies process ID.

       -n, --adjust value
           Specify the adjust score value.

       -h, --help
           Display help text and exit.

       -V, --version
           Print version and exit.

NOTES

       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.

AUTHORS

       Karel Zak <kzak@redhat.com>

SEE ALSO

       proc(5)

REPORTING BUGS

       For bug reports, use the issue tracker at https://github.com/util-linux/util-linux/issues.

AVAILABILITY

       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/>.