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From: Michael Smith <msmith@atrad.adelaide.edu.au>
Message-Id: <199605080957.TAA28588@genesis.atrad.adelaide.edu.au>
Subject: Re: serial errors
To: cslye@info.infosite.com (Cameron Slye)
Date: Wed, 8 May 1996 19:27:34 +0930 (CST)
Cc: freebsd-hackers@FreeBSD.ORG
In-Reply-To: <199605080602.XAA25101@info.infosite.com> from "Cameron Slye" at May 7, 96 11:02:12 pm
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Cameron Slye stands accused of saying:
> 
> Seem to be getting these errors with some software we are tring to use... 
> It is using the port at 115200, and I have set the speed of the device to
> 115200 and still seems to happen... This is on a p133 with 32mb, doing
> nothing else.  So I don't think IO is a problem.  Any ideas ?
> And I have pages of these errors...  TIA.
> 
> 
> May  7 15:41:59 nfs1 /kernel: sio0: 168 more tty-level buffer overflows (total 43853)
> May  7 15:45:21 nfs1 /kernel: sio0: 3051 more tty-level buffer overflows (total 46904)
> May  7 15:45:37 nfs1 /kernel: sio0: 184 more tty-level buffer overflows (total 47088)
> May  7 15:45:47 nfs1 /kernel: sio0: 72 more tty-level buffer overflows (total 47160)

Your application is spending too long doing something else, and not reading
from the device often enough.

>   /* detach from terminal if not debugging */
>   if ((!debug) && (!monitor))
>   {
>     if (fork())
>       exit(0);
>     for (i = 10; i >= 0; i--)
>       (void) close(i);
>     (void) open("/dev/null", O_RDONLY);
>     (void) dup2(0, 1);
>     (void) dup2(0, 2);
>     i = open("/dev/tty", O_RDWR);
>     if (i > 0)
>     {
>       (void) ioctl(i, TIOCNOTTY, (char *)NULL);
>       (void) close(i);
>     }
>   }

daemon() does most of this for you.

>   for (;;)
>   {
>     new_log_file();		/* if needed */
>     if (rx_data())
>       process_data();
>   }  

process_data() is taking too long, and the device talking to you is
not honouring the flow control that the sio driver will desperately
be asserting.


-- 
]] Mike Smith, Software Engineer        msmith@atrad.adelaide.edu.au    [[
]] Genesis Software                     genesis@atrad.adelaide.edu.au   [[
]] High-speed data acquisition and      (GSM mobile) 0411-222-496       [[
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