I came across this on the Fedora devel list. I added /etc/sysctl.d/51-bufferbloat.conf containing the suggested line and it installs the new codel qdisc as desired. There's probably more knobs that might be useful to tweak but this makes a good start. More reading on the bufferbloat site suggests that the later "cake" module will be even better, but it requires a newer kernel than CentOS currently ships with. <https://lists.fedoraproject.org/pipermail/devel/2015-March/209508.html> # 51-bufferbloat.conf # Address bufferbloat net.core.default_qdisc = fq_codel