sftp performance problem, cured by TCP_NODELAY

Miklos Szeredi miklos at szeredi.hu
Wed Jan 25 23:49:04 EST 2006

> So, if the code knows it is going to inject N requests at one time,
> why not use writev() or sendmsg()?

No, it keeps N requests outstanding all the time, meaning, that when a
reply comes back, it sends out another request.  I think this is
causing the problem.

However the problem is more general, in that ssh should be able to
efficiently transport _any_ kind of protocol, no matter what I/O
pattern it uses.

Does Nagle make sense for anything other than interactive sessions?

Maybe turning it off if input/output is not a terminal makes sense, no?


More information about the openssh-unix-dev mailing list