Control groups, or cgroups, are a way in Linux to control processes' hardware resource utilization by defining the resources limits, grouping them in a hierarchical structure and assigning processes to them. Cgroups can be used, in particular, to specify the skb priority of all network packets generated by a specific process. This provides a convenient way to prioritize network traffic generated in communication with the WHLE board itself (as opposed to the traffic passing through it when it’s used as a router, a case described in Ssh Prioritization (iptables)).

Cgroups perparation

mkdir /sys/fs/cgroup/net_prio
mount -t cgroup -o net_prio none /sys/fs/cgroup/net_prio
mkdir /sys/fs/cgroup/net_prio/prio-{0..15}
for p in {0..15}; do
    for if in $(cd /sys/class/net/; ls); do
        echo "${if} ${p}" > /sys/fs/cgroup/net_prio/prio-${p}/net_prio.ifpriomap
    done
done