Date: Sat, 4 Dec 1999 09:36:30 -0800 (PST) From: Matthew Jacob <mjacob@feral.com> To: Mike Smith <msmith@FreeBSD.ORG> Cc: hackers@FreeBSD.ORG Subject: Re: tty level buffer overflows Message-ID: <Pine.BSF.4.10.9912040854180.27711-100000@beppo.feral.com> In-Reply-To: <199912040758.XAA00511@mass.cdrom.com>
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> Er, you should read the sio(4) manpage too. tty-level buffer overflows
> have nothing to do with interrupt latency/execution time.
You mean this:
sio%d: tty-level buffer overflow. Problem in the application. Input has
arrived faster than the given module could process it and some has been
lost.
Normally I might agree with this, but I use a tty line on a 150Mhz i386 to
be a serial console for another freebsd box. This is a NS16550A with a 16
byte fifo. This systems is effectively idle except for this task. So, I'm
running tip and I get constant tty-level buffer overflows at 9600 baud.
I also have a 8 (well, 6 now since I moved and one of the system boards
blew a backplane interface chip) 50 Mhz processor SS1000 running Solaris
2.6. It has 5 Zilog (2 byte fifo) 8530 chips running constant console
sessions with regular large amounts of output (debugging and panicing
other solaris systems for Fibre Channel work) via tip. There has never
been a lost character that I can see except due to power outage. I am
convinced to a moral certainty and beyond a reasonable doubt that if I had
a single 50Mhz processor I'd have the same experience.
Since the Solaris tip and the FreeBSD tip are essentially identical (both
derive from BSD 4.X tip), I'd like to try and understand how this is an
application problem :-).
-matt
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