|
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | NOTES | AUTHORS | SEE ALSO | AVAILABILITY | COLOPHON |
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 <kzak@redhat.com>
proc(5)
The choom command is part of the util-linux package and is available
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
util-linux@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
2020-08-13. (At that time, the date of the most recent commit that
was found in the repository was 2020-08-12.) 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
man-pages@man7.org
util-linux April 2018 CHOOM(1)
Pages that refer to this page: proc(5) , procfs(5)