Date: Fri, 01 Sep 2000 12:53:12 -0600 From: Warner Losh <imp@village.org> To: "Jim King" <jim@jimking.net> Cc: "Gary Kline" <kline@thought.org>, freebsd-stable@FreeBSD.ORG Subject: Re: bad 16550A maybe? Message-ID: <200009011853.MAA37372@harmony.village.org> In-Reply-To: Your message of "Fri, 01 Sep 2000 13:41:01 CDT." <002d01c01444$350c8b00$a44b8486@jking> References: <002d01c01444$350c8b00$a44b8486@jking> <200009010501.WAA54972@tao.thought.org> <200009011832.MAA37168@harmony.village.org>
next in thread | previous in thread | raw e-mail | index | archive | help
In message <002d01c01444$350c8b00$a44b8486@jking> "Jim King" writes: : I think we'd see a lot fewer of these messages on the mailing lists if sio.c : set the 16550A trigger level to 8 bytes instead of 14 bytes. That's the : first thing I do when I see this problem, and that usually fixes it; much : easier than replacing the misbehaving hardware. :-) For fast machines, this is a lose since it double the interrupt rate, but does give a *MUCH* better interrupt latency tolerance. I had to do this when i had a 16550A attached to a custom card via PCI. I couldn't make it have fast interrupts, so I did the next best thing by increasing the number of interrupts and checking more often (the card itself had about half a dozen interrupts going all the time, so long as I could afford a 16ms latency I was fine). Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200009011853.MAA37372>