General whining about slowness of 3b1....

[Alex Crain]

In article <509 at flatline.UUCP>, erict at flatline.UUCP (J. Eric Townsend) writes:

> In the time it takes this program to run on a 3b1 (w/ only kermit running
> in the background) I kermited the source to the vax at UH at 1200bps,
> compiled it, linked it ran it, and read the output (21K) at 1200 bps.

	Sounds like your pascal compiler to me. The 3b1 is no speed demon,
but I've found that it benchmarks at about 90% of the speed of a 
VAXstation 2000. I've done supstancial programming in C and Lisp on this 
machine and found it to be generally faster then an 11/785 with 10 users.

	The real speed killer with this box is the single DMA line, which 
means that only one I/O device can happen at any given moment. THis makes
the machine I/O bound, a real problem if you have a 9600 baud line on tty000,
which will cause the cpu to interrupt itself to death. No fix for this that
I know of.

	THe other problem is usually lack of memory. The difference between
.5 meg and 2 meg is pretty amazing. I would encourage anyone to add all the 
memory that they can afford, and maybe a fast disk (if you don't have one now).
More memory will prevent swapping, thus limiting disk I/O to file handleing,
thus freeing up the DMA channel for the modem/serial line.

					:alex
Alex Crain
Systems Programmer			alex at umbc3.umbc.edu
Univ Md Baltimore County		umbc3.umbc.edu!nerwin!alex