Christoph Lameter has spent years improving Linux for high-performance
computing tasks.  During the memory-management track of the 2019 Linux
Storage, Filesystem, and Memory-Management Summit, he talked about the
problem of keeping up with a 400Gb/s network interface.  At that speed,
there simply is no time for the system to get its work done.  Some ways of
improving the situation are in sight, but it's a hard problem overall and,
despite some progress, the situation is getting worse.