Well guys,
It maybe MacOS... but I had a Mac][ running a 36k at full speed under MacOS,
28k8 and 33k6 run well with a MacIIci too. With nullmodem you can open 57.6k
without problems, even when i transfer to my Portable! Quadra840 and IIfx
have wonderful fast serial ports. Of course you need a cable that supports
Handshaking! My IIfx drives a 56k modem without problems and my Quadra840
does even better. So the ports MAY work fast. ANd my old 386 Vectra box I
had once was always lousy....
I never used much NetBSD serials because it doesn't run on my IIfx and i
learned to do quite everything under MacOS. But heck even on the Quarda i
remember that null-modem was bad over 9600!

bye to all and merry Xmas

riccardo

on 12/20/00 9:44 PM, Halim Chtourou at halim@onemain.com wrote:

> I've read quite a few archived discussions on PPP performance in
> NetBSD/mac68k.  From what I've seen, it seems very hard for the system
> to keep up with any serial connections over 38400. I am using a
> Quadra/Centris 660AV (25mhz '040) with 52MB ram and a SupraExpress 56
> external modem. My NetBSD Mac is only able to reach about half the
> throughput speed (between 2.5k/sec and 3.0k/sec usually) as my G4 with
> internal modem, and even PC with a cheap Motorola winmodem (both can
> reach 4.5-5k/sec and higher).
> 
> I am using my NetBSD Centris box as a router with IPNAT for 2 other
> computers on an ethernet network. It is running a 1.4.3 kernel that I
> compiled myself (with unnecessary drivers stripped out and -O3 and
> -m68040 optimizations).  During heavy network activity, even when the
> NetBSD box is idle, I still get many silo overflows:
> Dec 19 14:22:50 littleone /netbsd: zstty0: 14 silo overflows, 0 ibuf
> floods
> Dec 19 14:23:50 littleone /netbsd: zstty0: 9 silo overflows, 0 ibuf
> floods
> Dec 19 14:24:51 littleone /netbsd: zstty0: 13 silo overflows, 0 ibuf
> floods
> Dec 19 14:25:50 littleone /netbsd: zstty0: 4 silo overflows, 0 ibuf
> floods
> Dec 19 14:27:44 littleone /netbsd: zstty0: 9 silo overflows, 0 ibuf
> floods
> Never had an ibuf flood though.
> Those results are when the system is idle, I have gotten over 100 silo
> overflows in a minute during heavy system activity.
> 
> I have tried various port speeds, including 57600, 115200, and even
> 230400, all with similar results. (although overflows seem to occur most
> at 230400). I have also tried both cdtrcts and crtscts flow control
> options. Is this problem simply due to a lack of support for Serial DMA
> in NetBSD/mac68k? If so, can we ever expect to see this added in the
> (near?) future?
> 
> I have also tried various modem init strings, including disabling modem
> compression and setting the S26 register (RTS->CTS delay time), with no
> luck.
> 
> I would love to be able to use my NetBSD system for this, but unless I
> can find a solution to this speed problem, I have to just put it out in
> the shed to collect dust...
> 
> -Halim Chtourou
>