For clarity: The HFT space does things like CPU pinning (the cores their tasks run on are cut out of the main cgroup into a dedicated one for their tasks). Likewise, memory regions are preallocated and static. Important resources like network stacks are done in user space - sure, the kernel has an IP address, for the 1g nic that's used for management, but the IB card that powers the trading interconnect (you are less likely to find IB these days, so listen to my story as a little dated) is mapped directly into userspace; there's no driver for it in the kernel.
