Lots of useful information can be found in:
http://keithp.com/~keithp/talks/usenix2003/
On Tue, 2004-05-11 at 02:09, Dr Andrew C Aitchison wrote:
> On Tue, 11 May 2004, Suresh wrote:
>
> > Hi,
> >
> > Has anyone come across X applications re-engineered for low bandwidth networks,
> > This in the context of thin clients.
>
> Low bandwidth or high latency ?
>
> Keith Packard and Jim Gettys have done some work on X clients
> as well as their work on low bandwidth X servers.
> If my memory is reliable, Owen Taylor did some work optimizing
> clients, possibly in the context of Motif.
>
> The low bandwidth case is essentially solved:
> avoid using lots of images
> ssh compression can help a lot
SSH compression ("ssh -C") makes a factor of 300(!)
difference in bandwidth used in a gnome session startup,
(a pretty vanilla set of applications).
> the LBX extension might be worth trying, too
> with this combination, a fast modem connection (say 33Kbps)
> isn't painful in terms of bandwidth.
LBX never does better than "ssh -C". Don't bother with LBX;
you need the security ssh provides these days anyway.
>
> What does kill X performance, even on cable modems (say 512Kbps)
> is latency. Especially at start up many X libraries make lots of
> round trip requests in serial.
> I don't remember the details, but you want to try to batch
> these requests, so that you get lots of answers in each round trip.
> (A way of making them in parallel would be nice too :).
Client side fonts have helped (eliminated more than 25%
of round trips).
Work in the toolkits is also helping. GTK+ now batches
intern atom, for example. Some other egregious bugs in
toolkits have been/are being fixed as a result of
the data.
There are other things we can and should do to help
things further.
If we do everything that should be done, we can eliminate
about 90% of the round trips, ultimately. But the low
hanging fruit is about 50% of the round trips we had
a year or so ago; the remaining will take some more
serious work, as outlined in the paper.
- Jim
--
Jim Gettys <[EMAIL PROTECTED]>
HP Labs, Cambridge Research Laboratory
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