High latency with Linux clients - or "It's always the Nagle's Algorithm" about ocaml-cohttp

[ansiwen]

@TheLortex @haesbaert @dinosaure pinging you, because you guys helped me before with other TCP/IP related issues. 😬

[ansiwen]

I can indeed disable the Nagle's Algorithm and make the issue disappear by using a Stack wrapper like this:

module Stack_nodelay (Stack : Tcpip.Stack.V4V6) = struct
  include Stack
  module TCP = struct
    include Stack.TCP
    let write = Stack.TCP.write_nodelay
    let writev = Stack.TCP.writev_nodelay
  end
end

However, as I mentioned above, even with ~flush:false it creates three separate "tinygrams" for one response.

[ansiwen]

I found one of the problems:

ocaml-cohttp/cohttp-mirage/src/io.ml

Lines 60 to 62 in daf1323

	let flush _ =
	(* NOOP since we flush in the normal writer functions above *)
	Lwt.return_unit

Is there a reason why every write in cohttp-mirage is flushed @avsm ?