1CHOOM(1)                         User Commands                        CHOOM(1)
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NAME

6       choom - display and adjust OOM-killer score.
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8       choom -p PID
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10       choom -p PID -n number
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12       choom -n number [--] command [argument ...]
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DESCRIPTION

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

19       -p, --pid pid
20           Specifies process ID.
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22       -n, --adjust value
23           Specify the adjust score value.
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25       -h, --help
26           Display help text and exit.
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28       -V, --version
29           Print version and exit.
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NOTES

32       Linux kernel uses the badness heuristic to select which process gets
33       killed in out of memory conditions.
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35       The badness heuristic assigns a value to each candidate task ranging
36       from 0 (never kill) to 1000 (always kill) to determine which process is
37       targeted. The units are roughly a proportion along that range of
38       allowed memory the process may allocate from based on an estimation of
39       its current memory and swap use. For example, if a task is using all
40       allowed memory, its badness score will be 1000. If it is using half of
41       its allowed memory, its score will be 500.
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43       There is an additional factor included in the badness score: the
44       current memory and swap usage is discounted by 3% for root processes.
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46       The amount of "allowed" memory depends on the context in which the oom
47       killer was called. If it is due to the memory assigned to the
48       allocating task’s cpuset being exhausted, the allowed memory represents
49       the set of mems assigned to that cpuset. If it is due to a mempolicy’s
50       node(s) being exhausted, the allowed memory represents the set of
51       mempolicy nodes. If it is due to a memory limit (or swap limit) being
52       reached, the allowed memory is that configured limit. Finally, if it is
53       due to the entire system being out of memory, the allowed memory
54       represents all allocatable resources.
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56       The adjust score value is added to the badness score before it is used
57       to determine which task to kill. Acceptable values range from -1000 to
58       +1000. This allows userspace to polarize the preference for oom killing
59       either by always preferring a certain task or completely disabling it.
60       The lowest possible value, -1000, is equivalent to disabling oom
61       killing entirely for that task since it will always report a badness
62       score of 0.
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64       Setting an adjust score value of +500, for example, is roughly
65       equivalent to allowing the remainder of tasks sharing the same system,
66       cpuset, mempolicy, or memory controller resources to use at least 50%
67       more memory. A value of -500, on the other hand, would be roughly
68       equivalent to discounting 50% of the task’s allowed memory from being
69       considered as scoring against the task.
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AUTHORS

72       Karel Zak <kzak@redhat.com>
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SEE ALSO

75       proc(5)
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REPORTING BUGS

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

82       The choom command is part of the util-linux package which can be
83       downloaded from Linux Kernel Archive
84       <https://www.kernel.org/pub/linux/utils/util-linux/>.
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88util-linux 2.38.1                 2022-05-11                          CHOOM(1)
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