sftp performance problem, cured by TCP_NODELAY

Damien Miller djm at mindrot.org
Thu Jan 26 14:19:07 EST 2006

Miklos Szeredi wrote:
>>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?

http://bugzilla.mindrot.org/show_bug.cgi?id=556 has been there for a
while, but nobody commented on it.

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