superlifter design notes and a new proposal

Martin Pool mbp at
Mon Aug 5 20:13:01 EST 2002

On  5 Aug 2002, Paul Haas <paulh at> wrote:

> > Fast networks are a significant use case that ought to be considered.
> > On GigE, having low processing overhead and being able to use things
> > like sendfile() to transmit data are going to be enormously more
> > important than the length of the header.
> Which is another situation where compression code in rsync may not be a
> win.
> Is there a big real world CPU penalty for letting ssh do the
> compression?

I doubt it.

> That would mean uncompressed bits go over the local socket, but the
> network links are compressed.

These two extremes are what lead me to think that micro-optimizing the
headers is not a good idea.

 - for fast networks, being quick to handle (i.e. aligned, fixed-size)
   is more important than size

 - for ssh, you have to compress anyhow, so bumming bytes out is not


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