Maybe what it was (quoting from memory) is that the timeout for re-ordering/assembly started at 30 seconds (not 120 per the RFC) and only increased up to a limi

Maybe what it was (quoting from memory) is that the timeout for re-ordering/assembly started at 30 seconds (not 120 per the RFC) and only increased up to a limit of 180 when the kernel thought it wasn't something bursty like DNS; some kind of heuristic probably introduced to make NFS pre v4 work better. Maybe the queues were too small when MTUs could be 1500 bytes or less?