I have recently tracked down a number of networking issues caused by cgroups introducing network stalls in certain scenarios. There were a number of patches submitted to upstream in v6.x to fix these issues. It is a constant pain seeing such fundamental networking issues still occurring in the latest linux kernel versions. On one hand I would like to track bleeding edge kernel releases to get the latest fixes and performance improvements, but on the other hand I do not have enough resources to maintain our own kernel builds and patches.