[plug] Slow Serial Port

[Robert Andrews]

Thanks Pete I will check irqtune I have just about read all there is to read
I been punching keyboards for about 26 years now have built a lot of comps
but Ive only been into Linux for about 12 months (still a newbie)

This is a Linux only machine so unless I install windows on it I cant test
in that enviroment
Im sure its a software problem as I said i have change motherboards and cpu
its now a K6-230

----- Original Message -----
From: Peter Wright <pete at cygnus.uwa.edu.au>
To: <plug at plug.linux.org.au>
Sent: Monday, April 23, 2001 9:04 PM
Subject: Re: [plug] Slow Serial Port


> On Mon, Apr 23, 2001 at 08:15:55PM +0800, Linux wrote:
> > Hi all
> > I have a problem that I have not been able to resolve and need some help
please
> > I have been trying to fix this for months
> >
> > The problem is my second serial port ttyS1 seems to get hung up almost
> > like it has a irq problem.  I can dial into my modem on ttyS0 and there
> > is no problem When I dial into ttyS1 I get 45%-90% packet loss pings are
> > 140/ms
> [ snip ]
> > Things I have done or know and have made no difference
> [ snip ]
> > I have used setserial and tried lots of combinations
> > Useing ttyS1 as the dial out port yeilds the same results (huge packet
loss)
> [ snip ]
> > There must be something I have missed or can do
> > Any help would be greatly appreciated
>
> This is almost certainly not what you want to hear :), but even in my
> not-hardware-expert opinion it does sound very much like a hardware
> problem. Unless you have other information that suggests the hardware is
> fine? (eg. the same serial port works fine under Windows)
>
> Well, if you haven't, I'd suggest you try just that (dialing out through a
> modem on your second serial port (the problem one) under Windows. If the
> problems present under Linux are also apparent under Windows, your ttyS1
is
> _probably_ dysfunctional and you'd need someone with reasonable hardware
> knowledge/skills to have a chance at fixing it.
>
> *pause as I have another look at Bob's email*
>
> Hang on a tick... you also said (which I initially missed, d'oh!):
>
> > I have tried disabling the second onboard serial port and fitted a
serial
> > i/o card and tried all possable irq settings i/e  3-4-5
>
> Okay - so I presume this didn't work - in what way didn't it work?
> If you'd disabled the second onboard serial port (how?) /dev/ttyS1
> shouldn't exist... but does /dev/ttyS2 exist then?
>
> > I have disabled the mouse GPM
> > I have changed motherboards and CPU
>
> Now this is the one that really gets me. You've changed _motherboards_ (so
> you've essentially got different serial port hardware) and the problem
> still exists? Damn, then I am completely off track with my suggestions
> above, it must be a software issue. Pardon me while I go headbut the desk.
> *thump* Ow.
>
> > I have used setserial and tried lots of combinations
>
> What CPU(s) and motherboard(s) are you dealing with?
>
> My housemate suggests playing around with irqtune. He has an older machine
> (386) that used to have severe lossage problems similar to those you
> describe above, dealing with just a single 14400K modem. He used irqtune
to
> (if I understand correctly) increase the priority of the serial interrupt.
> He now runs a 56K modem on it with no significant lossage.
>
> If you haven't already, I'd seriously recommend you check the Serial
HOWTO:
>
> http://www.linuxdoc.org/HOWTO/Serial-HOWTO.html
>
> It's flooded with heaps of useful information and a lot of troubleshooting
> tips. The HOWTO also mentions irqtune under "Troubleshooting Tools":
>
>   "irqtune" will give serial port interrupts higher priority to improve
>   performance.
>
> > Regards Bob Andrews
>
> Hope some of the above helps. Good luck,
>
> Pete.
> --
> http://cygnus.uwa.edu.au/~pete/
>
> --
> hundred-and-one symptoms of being an internet addict:
> 136. You decide to stay in a low-paying job teaching just for the
>      free Internet access.
>
>