The memory control group (memcg) quality of service (QoS) can be used to control locks
and limits on memory usage in a memcg. In community versions of the Linux kernel,
this feature is supported only in the
cgroup v2 interface, whereas in Alibaba Cloud Linux 2 kernel version
4.19.91-18.al7 or later, this feature is also supported in the
cgroup v1 interface.
In the Alibaba Cloud Linux 2 kernel, the
memcg QoS feature is enabled in the
cgroup v1 interface by default. For more information about
memcg QoS, visit
Documentation/admin-guide/cgroup-v2.rst. You can obtain the kernel document from the Debuginfo package and the source code
package of Alibaba Cloud Linux 2. For more information, see Use Alibaba Cloud Linux 2.
When you use the memcg QoS feature of the
cgroup v1 interface, we recommend that you place your tasks in a memcg leaf node such as /sys/fs/cgroup/memory/<intermediate node>/<leaf node>/tasks.
This section describes the interface files that implement the memcg QoS feature of
cgroup v1 interface in the Alibaba Cloud Linux 2 kernel.
|memory.min||Absolutely locks the memory. Memory locked by this interface file is not reclaimed
even if the system has no memory to reclaim. You can perform the following read and
write operations on this file:
|memory.low||Relatively locks the memory. Memory locked by this interface file may be partially
reclaimed if the system has no other memory to reclaim. You can perform the following
read and write operations on this file:
|memory.high||Limits the memory usage. You can perform the following read and write operations on
Create a test memcg at the memcg mount point such as /sys/fs/cgroup/memory/, and ensure that the memcg includes the memory.min, memory.low, and memory.high interface files.
The following sample commands are provided for your reference:
mkdir /sys/fs/cgroup/memory/test ls /sys/fs/cgroup/memory/test | grep -E "memory.(min|low|high)"
Sample command outputs:
memory.high memory.low memory.min