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Date:      Tue, 8 Jun 1999 11:48:52 -0500 (CDT)
From:      Doug Jennings <dougj@netdoor.com>
To:        "James R. Shrenk" <dionysos3@crosswinds.net>
Cc:        Mark Ovens <markov@globalnet.co.uk>, freebsd-questions@FreeBSD.ORG
Subject:   Re: silo overflow errors
Message-ID:  <Pine.GSO.4.10.9906081138260.26779-100000@lance.netdoor.com>
In-Reply-To: <Pine.BSF.4.05.9906080036410.6452-100000@neptune.twrol.com>

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I am now positive that it is not the modem's fault.  I installed Win 98
and the modem is performing quite nicely -- even downloading at 3 k/sec
at times.  

When originally trying to configure and dial out with user ppp, I noticed
that my CPU usage was skyrocketing to 90% (and I have a PII 450, so this
concerned me to say the least) -- but this only seemed to happen during a
failed dial attempt.  I am fairly new at BSD, so it took me a day or two
to get my modem and ppp.conf playing along nicely.  I will check and see
if the CPU usage is still as high as it was then.

Do you know where I can get some info on how to resolve the problem if it
is an IRQ issue?


You guys have been really helpful, and I thank you for it.

More later, I am sure.

-Doug


On Tue, 8 Jun 1999, James R. Shrenk wrote:

> looks good so far.  I took a visit around some man pages and the web and
> it seems unlikely that it's actually the modem that would be causing the
> problem.  Check the output of top during your ppp sessions.  In
> particular, what is your CPU usage during that time.  The data that's
> buffered in the UART seems to be dropping in this case.  The slow is then
> probably a result of packets being retransmitted to account for the
> errors.  The man page for 3.2-release says that these silo overflows are
> the result of a problem with the interrupt handler.  Although I'm sketchy
> on this, your serial port may not be getting enough attention from the CPU
> so it may be worth checking out.
> 
> James
> 
> On Mon, 7 Jun 1999, Mark Ovens wrote:
> 
> > On Mon, Jun 07, 1999 at 05:17:53PM -0500, Doug Jennings wrote:
> > > When I get the output of dmesg, it contains the following lines:
> > > 
> > > sio0 at 0x3f8-0x3ff irq 4 flags 0x10 on isa
> > > sio0: type 16550A
> > > 
> > > I knew it had to be a 16550A UART because the computer is brand new with all
> > > the appropriate bells / whistles / et cetera.  Argh.  I suppose I will see
> > > if I can slow down the modem now.
> > > 
> > > One more question...do you think the problem is happening inside the modem
> > > itself?  Or could it be caused by some kind of interference in my serial
> > > cable?
> > 
> > It would be worth checking the shield on your cable, especially if
> > it runs parallel to the mains lead. I've seen silo overflow errors
> > generated at the rate of >50 per second on a Sun with serial lines
> > to terminals running through a factory close to arc welders :-)
> > 
> > > I am obviously grasping here, but I just can't figure out why I am
> > > having silo errors with such a supposedly good modem (external courier
> > > v.everything 28800).
> > > 
> > > >What is your dmesg output?  It looks like you might have a older UART
> > > >(8250 maybe?)  If that's the case, you might try slowing the modem down to
> > > >14400 and see if that doesn't help.
> > > >
> > > >
> > > >On Mon, 7 Jun 1999, Doug Jennings wrote:
> > > >
> > > >>
> > > >> After finally getting user ppp to work, I keep running into the
> > > >> following problem.  Once I establish a ppp connection and I try to
> > > >> send/receive any data whatsoever  (for example, opening a telnet
> > > session), I
> > > >> get the message:
> > > >>
> > > >> /kernel:  sio0:  1 more silo overflow (total 1)
> > > >>
> > > >> The 'total' goes up each time I send/receive any data (for example, if I
> > > >> issue a "ls" command in the telnet session and have to receive the output
> > > of
> > > >> that).  It slows down my 28800 modem to an absolute crawl.
> > > >>
> > > >> Any ideas on a fix for this? I am running a fresh installation of FreeBSD
> > > >> 3.1 and I am using an external USR v.everything courier modem.  I know
> > > that
> > > >> it has to do with some buffering issue -- I just don't know how to fix
> > > it.
> > > >>
> > > >> Any ideas would be appreciated.



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