2.9 BSD uucico slowness

[Larry Cohen]

Here at decvax we will do anything to speed up uucico.
We also noticed that in the pk routines, several "reads"
were necessary to pull a packet off the network.  On the
average there were about 3 context switches per packet on
a 1200 baud line.  Of course this varied with the time of
day and speed of the line.  One "experiment" we tried was
to try a modified Berknet line discipline.  This line discipline
would read a specified number of characters and not return until
they all had arrived.  Internally it used circular queues. It
does not use clists at all.
The improvement was pretty good. 
I dont have the exact figures with me (I'm at home 4 months
after I ran the experiments) but It was something
in the ballpark of about 20 % improvement in overall throughput.
33 % reduction in context switches.  Less time was spent in the system,
and the user time was less also.  There was no reduction in performance
on 9600 baud lines.  I hope to try running on decvax before long.
						-Larry Cohen