"NB: Recent versions of Linux (version 2.6.17 and later) have full autotuning with 4 MB maximum buffer sizes. Except in some rare cases, manual tuning is unlikely to substantially improve the performance of these kernels over most network paths, and is not generally recommended
All system parameters can be read or set by accessing special files in the /proc file system. E.g.:
If the parameter tcp_moderate_rcvbuf is present and has value 1 then autotuning is in effect. With autotuning, the receiver buffer size (and TCP window size) is dynamically updated (autotuned) for each connection. (Sender side autotuning has been present and unconditionally enabled for many years now)."