docker - 如何限制容器内存大小？

Question

我分别用两种linux系统部署Docker0.8，都没法限制容器的内存大小。具体情况如下：

1. 用CentOS6.5【内核为3.10.5-3.el6.x86_64】做主机，新建容器，得到结果如下：

# docker run -i -t -d -m 512m centos /bin/bash   
WARNING: WARNING: Your kernel does not support swap limit capabilities. Limitation discarded.
9229fe1bac59992337e909cbc5a11f3e0fa81553ad7b136bec95a62181a251fd

该容器新建成功，但不能限制内存大小。

1. Ubuntu 12.04【内核为3.8.0-38-generic】做主机，并且修正/etc/default/grub,更改$ GRUB_CMDLINE_LINUX="cgroup_enable=memory swapaccount=1"之后，新建容器，得到结果如下：

# sudo docker run -i -t -m 512m -d ubuntu /bin/bash
89d629ed37d63b67b49ed8c4c11cab653d61d5b85227bdd10c8a9a0a718c686e

看似未报错，登陆该新建的容器里面查看内存【free命令】，发现并未限制。

大家手头的主机都是什么系统，有没有这种情况？如何解决？盼回复，谢谢！

Answer 1

The memory on

in the free命令，看的是Hostcontainer.

To check the memory limit of container use this:

cat /cgroup/memory/lxc/{full_container_id}/memory.limit_in_bytes

You can also check the restrictions of other resources under

/cgroup/:

ll /cgroup/
总用量 0
drwxr-xr-x 3 root root 0 3月  17 13:33 blkio
drwxr-xr-x 3 root root 0 3月  17 13:33 cpu
drwxr-xr-x 3 root root 0 3月  17 13:33 cpuacct
drwxr-xr-x 3 root root 0 3月  17 13:33 cpuset
drwxr-xr-x 3 root root 0 3月  17 13:33 devices
drwxr-xr-x 3 root root 0 3月  17 13:33 freezer
drwxr-xr-x 3 root root 0 3月  17 13:33 memory
drwxr-xr-x 3 root root 0 3月  17 13:33 net_cls

Answer 2

Owner, I also encountered this problem when I was doing experiments with Ubuntu virtual machine. Please refer to here to solve it
http://docs.docker.com/articles/runmetrics/
The following are key excerpts

If you want to enable memory and swap accounting, you must add the following command-line parameters to your kernel:

$ cgroup_enable=memory swapaccount=1

On systems using GRUB (which is the default for Ubuntu), you can add those parameters by editing /etc/default/grub and extending GRUB_CMDLINE_LINUX. Look for the following line:

$ GRUB_CMDLINE_LINUX=""

And replace it by the following one:

$ GRUB_CMDLINE_LINUX="cgroup_enable=memory swapaccount=1"

Then run sudo update-grub, and reboot.

These parameters will help you get rid of the following warnings:

WARNING: Your kernel does not support cgroup swap limit.
WARNING: Your kernel does not support swap limit capabilities. Limitation discarded.

Answer 3

Does anyone know how to solve this problem on Centos6?
My docker is 1.6.2, Centos is 6.6, and the kernel version is 3.10.81

Answer 4

@colin5063

I am CentOS6.7, it should be almost the same

I modified it/etc/grub.conf 在当前使用的内核的kernel项的最后加上cgroup_enable=memory swapaccount=1

reboot

Then cat /proc/cmdline you will find that the configuration has taken effect