Question

I’m encrypting data on the fly and writing it to a network stream.

Should I write to the stream as soon as each 16-byte encrypted block data becomes available or should I buffer it? Is there a performance penalty to sending bunches of 16 byte writes rather than a single 20 kilobyte or 1 megabyte write?

Answer 1

Feed it as much as you have, It will let you know if it can’t take any more. TCP will handle the buffering for you.

Also, the more you feed – the better, it will likely result in less traffic as packets will not be fragmented much.

By default Socket uses Nagle algorithm, which is designed to reduce network traffic by causing the socket to buffer small packets and then combine and send them in one packet under certain circumstances. A TCP packet consists of 40 bytes of header plus the data being sent. When small packets of data are sent with TCP, the overhead resulting from the TCP header can become a significant part of the network traffic. On heavily loaded networks, the congestion resulting from this overhead can result in lost datagrams and retransmissions, as well as excessive propagation time caused by congestion. The Nagle algorithm inhibits the sending of new TCP segments when new outgoing data arrives from the user if any previously transmitted data on the connection remains unacknowledged.

You can turn off Nagle algorithm, but this will likely result in more fragmentation and traffic.