Very Computer

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.

Dan

[Posted and mailed]

 : 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)

AFAIK, the installation stuff uses ppp over tun0.

 : 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 ...

Hmm, this is normally due to a dodgy UART or a flow control problem.

 : 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!

Looks like flow control :-|

 : 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.

Make sure that your modem is talking RTS/CTS and that your port is
stty'd with crtscts.

 : Dan
 :

--

      <http://www.Awfulhak.org>
Don't _EVER_ lose your sense of humour !

: [problems with sio buffer overflows]

I've solved my little problem with help from some FreeBSD users. Many
thanks (sorry - I don't have names handy). If anyone else has sio
problems, try these:

1. Make sure ctsrts option is set in your PPP config file.
   ("set ctsrts on" in your /etc/ppp/ppp.conf file) Use
   "stty -f DEVICE" to check, where DEVICE is the /dev
   device your modem hangs off.

2. Make sure your modem is using ctsrts flow control and not xon/xoff
   or no flow control. Save the setting so it is used by default on
   power on. This is not the same as 1 (*oops* :-) ).

3. Double check for IRQ/IO port/DMA conflicts.

4. Check for faulty hardware using a good diagnostics tool and
   loop-back connectors for the COM port. Check for genuine
   16550A and not plain old 16550.

If all else fails it was reccommended to upgrade to 2.2-STABLE,
altho I've got 2.2.5-RELEASE working OK now.

Anyway, thanks again to those who responded.

Dan