Cgroups - howto

Howto - cgroups

This is only for debian wheezy

Prereq

apt-get install cgroup-bin 

Enable cgroups memory configuration

This is disabled by default in wheezy (installed though), so activate via:

vim /etc/default/grub
# Add cgroup_enable=memory to GRUB_CMDLINE_KERNEL:
GRUB_CMDLINE_LINUX="cgroup_enable=memory"
update-grub2

Mount cgroups

Add to /etc/fstab

cgroup  /sys/fs/cgroup  cgroup  defaults  0   0

Create cgroup owner(s)

sudo cgcreate -a ipeacocks -g cpu:ipeacocks

• Adding ressources to that user. A CPU is divided into 1024 slices, so assigning 100 for a user would equal ~10%.

# About 10 % cpu
echo 100 > /cgroup/cpu/$USER/cpu.shares

# 10 Mb
echo 10000000 > /cgroup/memory/$USER/memory.limit_in_bytes

# -g specifies the control group to run the process in
# Limit cpu
cgexec -g cpu:$USER command <options> &

# Limit cpu and memory
cgexec -g memory,cpu:$USER command <options> &

If the above works fine, cgroups is setup successfully.

Setting up configurations

Edit /etc/cgconfig.conf, add your cgroups users

group $USER {
# Specify which users can admin (set limits) the group
perm {    
    admin {
        uid = $USER;
    }
# Specify which users can add tasks to this group
    task {
        uid = $USER;
    }
}
# Set the cpu and memory limits for this group
cpu {
    cpu.shares = 100;
    }
memory {
    memory.limit_in_bytes = 10000000;
    }
}