树莓派docker: Your kernel does not support memory limit capabilities or the cgroup is not mounted

在树莓派进行ttnode容器内存显示时，出现Your kernel does not support memory limit capabilities or the cgroup is not mounted. Limitation discarded.

docker update ttnode --memory-swap -1 -m 1024M
Your kernel does not support memory limit capabilities or the cgroup is not mounted. Limitation discarded.

解决

Docker 基于 Linux 内核提供的 cgroups 功能，可以限制容器在运行时使用到的资源，比如内存、CPU、块 I/O、网络等。
docker提示系统不支持cgroup内存限制，需要手动开启。
解决方案是在/boot/cmdline.txt尾部加入 cgroup_enable=memory cgroup_memory=1后重启
再次运行改动已生效