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diff --git a/sys-utils/choom.1 b/sys-utils/choom.1 new file mode 100644 index 0000000..2b844cb --- /dev/null +++ b/sys-utils/choom.1 @@ -0,0 +1,82 @@ +.TH CHOOM 1 "April 2018" "util-linux" "User Commands" +.SH NAME +choom \- display and adjust OOM-killer score. +.SH SYNOPSIS +.B choom +.B \-p +.I pid +.sp +.B choom +.B \-p +.I pid +.B \-n +.I number +.sp +.B choom +.B \-n +.I number +.IR command\ [ argument ...] + +.SH DESCRIPTION +The \fBchoom\fP command displays and adjusts Out-Of-Memory killer score setting. + +.SH OPTIONS +.TP +.BR \-p ", " \-\-pid " \fIpid\fP +Specifies process ID. +.TP +.BR \-n , " \-\-adjust " \fIvalue\fP +Specify the adjust score value. +.TP +.BR \-h ", " \-\-help +Display help text and exit. +.TP +.BR \-V ", " \-\-version +Display version information and exit. +.SH 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. + +.SH AUTHORS +.nf +Karel Zak <kzak@redhat.com> +.fi +.SH SEE ALSO +.BR proc (5) +.SH AVAILABILITY +The \fBchoom\fP command is part of the util-linux package and is available from +.UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/ +Linux Kernel Archive +.UE . |