diff options
Diffstat (limited to 'man/systemd.resource-control.xml')
| -rw-r--r-- | man/systemd.resource-control.xml | 57 |
1 files changed, 23 insertions, 34 deletions
diff --git a/man/systemd.resource-control.xml b/man/systemd.resource-control.xml index 3ccb5c4927..744a5f98ce 100644 --- a/man/systemd.resource-control.xml +++ b/man/systemd.resource-control.xml @@ -261,53 +261,42 @@ </varlistentry> <varlistentry> - <term><varname>MemoryMin=<replaceable>bytes</replaceable></varname></term> + <term><varname>MemoryMin=<replaceable>bytes</replaceable></varname>, <varname>MemoryLow=<replaceable>bytes</replaceable></varname></term> <listitem> - <para>Specify the memory usage protection of the executed processes in this unit. If the memory usages of - this unit and all its ancestors are below their minimum boundaries, this unit's memory won't be reclaimed.</para> - - <para>Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the specified memory size is - parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. Alternatively, a - percentage value may be specified, which is taken relative to the installed physical memory on the - system. If assigned the special value <literal>infinity</literal>, all available memory is protected, which may be - useful in order to always inherit all of the protection afforded by ancestors. - This controls the <literal>memory.min</literal> control group attribute. For details about this - control group attribute, see <ulink - url="https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</para> - - <para>This setting is supported only if the unified control group hierarchy is used and disables - <varname>MemoryLimit=</varname>.</para> - - <para>Units may have their children use a default <literal>memory.min</literal> value by specifying - <varname>DefaultMemoryMin=</varname>, which has the same semantics as <varname>MemoryMin=</varname>. This setting - does not affect <literal>memory.min</literal> in the unit itself.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>MemoryLow=<replaceable>bytes</replaceable></varname></term> - - <listitem> - <para>Specify the best-effort memory usage protection of the executed processes in this unit. If the memory - usages of this unit and all its ancestors are below their low boundaries, this unit's memory won't be - reclaimed as long as memory can be reclaimed from unprotected units.</para> + <para>Specify the memory usage protection of the executed processes in this unit. + When reclaiming memory, the unit is treated as if it was using less memory resulting in memory + to be preferentially reclaimed from unprotected units. + Using <varname>MemoryLow=</varname> results in a weaker protection where memory may still + be reclaimed to avoid invoking the OOM killer in case there is no other reclaimable memory.</para> + <para> + For a protection to be effective, it is generally required to set a corresponding + allocation on all ancestors, which is then distributed between children + (with the exception of the root slice). + Any <varname>MemoryMin=</varname> or <varname>MemoryLow=</varname> allocation that is not + explicitly distributed to specific children is used to create a shared protection for all children. + As this is a shared protection, the children will freely compete for the memory.</para> <para>Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the specified memory size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. Alternatively, a percentage value may be specified, which is taken relative to the installed physical memory on the system. If assigned the special value <literal>infinity</literal>, all available memory is protected, which may be useful in order to always inherit all of the protection afforded by ancestors. - This controls the <literal>memory.low</literal> control group attribute. For details about this - control group attribute, see <ulink + This controls the <literal>memory.min</literal> or <literal>memory.low</literal> control group attribute. + For details about this control group attribute, see <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#memory-interface-files">Memory Interface Files</ulink>.</para> <para>This setting is supported only if the unified control group hierarchy is used and disables <varname>MemoryLimit=</varname>.</para> - <para>Units may have their children use a default <literal>memory.low</literal> value by specifying - <varname>DefaultMemoryLow=</varname>, which has the same semantics as <varname>MemoryLow=</varname>. This setting - does not affect <literal>memory.low</literal> in the unit itself.</para> + <para>Units may have their children use a default <literal>memory.min</literal> or + <literal>memory.low</literal> value by specifying <varname>DefaultMemoryMin=</varname> or + <varname>DefaultMemoryLow=</varname>, which has the same semantics as + <varname>MemoryMin=<replaceable> and <varname>MemoryLow=<replaceable>. + This setting does not affect <literal>memory.min</literal> or <literal>memory.low</literal> + in the unit itself. + Using it to set a default child allocation is only useful on kernels older than 5.7, + which do not support the <literal>memory_recursiveprot</literal> cgroup2 mount option.</para> </listitem> </varlistentry> |