I've installed FreeBSD 2.2.5 on a 50Mhz 486 DX2 (12 Mb RAM).
During the install, I used the provided PPP interface (ppp0)
and got 3.2 Kb/sec throughput with my Netcomm 34F modem. I
used a line speed of 115K. All went well. Congrats to the FreeBSD
team on a very smooth install routine (well, I had some probs
but they were my fault!).
After installation and reboot I configured my machine to use
user-level PPP to dial in to my ISP. It connects fine and I
can ping remote hosts and telnet to them.
I tried to FTP a file however and got numerous sio errors
relating to "tty-level buffer overflows". My com port is
id'd by the kernel as a 16550A. When I ping'd the host, things
were fine, but if I used packet sizes greater than 4K, I got:
/kernel: sio0: 1221 more tty-level buffer overflows ...
In my ppp.conf, I had put "set line 115200", which was what I used
during the install (which went fine, and had no overflows). I
decreased the line speed to 57K, then 38K, then 28K and finally
14.4K before the buffer overflows disappeared completely. I
know get throughput of around 0.5 Kb/sec. Yuk!
The sio man page said a tty-level overflow was when the client
couldn't fetch the data out of the sio buffer quick enough.
The machine is not heavily loaded. Since I can use the 34K
modem under OS/2 Warp with a line speed of at least 57K, I
thought FreeBSD should be able to. So what am I doing wrong?
Is kernel level PPP quicker? (It will still use sio0 though,
won't it?) If 115K line speed and 3.2 Kb/sec is possible
during install, why doesn't it work now? Can anyone help?
Please e-mail suggestions as beofre, and I will post a summary
back to the group.