On Fri, Feb 15, 2008 at 12:13:07PM +0800, Kacheong Poon wrote: > Nicolas Williams wrote: > > > Question for networking-discuss: > > > > Is there an OpenSolaris project to auto-tune TCP send/receive buffer > > sizes? If so, what is its status? Certainly there exist TCP buffer > > size auto-tuning efforts outside OpenSolaris, such as [1] (among many > > others). > > > AFAIK, there is no on-going project. As for efforts in > other platforms, I know that both Linux and Windows Vista > have this.
We could implement auto-tuning in ssh/sshd, as a stopgap, I suppose, but that would be a new project and probably wouldn't get off the ground soon enough. I'm thinking that when an sftp channel exists then ssh/sshd could tune up the channel's window size and the TCP SNDBUF/RCVBUF sizes until the observed BDP stops growing. There's ways to measure RTTs in SSHv2 (I'm thinking of using bogus channel requests), see, and bandwidth is measurable in the SFTP case as well (though with better accuracy on the client-side), so we can measure BDP in ssh and sshd. Integrating sftp/sftp-server into ssh/sshd would help. But it'd be easier still to just get TCP auto-tuning from the TCP stack :) Nico --
