Date: Tue, 20 May 1997 12:51:59 -0600 From: Brett Glass <brett@lariat.org> To: rberndt@nething.com, WELCHDW@wofford.edu, HARDWARE@FreeBSD.ORG Cc: WELCHDW@wofford.edu Subject: Re: isa bus and boca multiport boards Message-ID: <3.0.1.32.19970520125159.006dbe70@lariat.org> In-Reply-To: <8825649D.00771D31.00@IWND1.infoworld.com>
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At 04:14 PM 5/20/97 -0400, you wrote: >Since the entire set of ports must be scanned whenever an interrupt occurs, >maybe there is too much delay in getting to the upper ports. Something gets >locked up if they overflow. I left several messages, but no one could >figure it out. Maybe the sio driver should be recoded in optimized ASM. I can see some major C inefficiencies in it, including lots of repeated pointer dereferences and control structures that the compiler would probably optimize poorly. I've generated super-tight assembler for serial I/O. A stopgap might be be use a couple of IRQs for the different ports, if the board lets you do it. I put no more than 4 UARTs on an IRQ in my system because the driver loops over the UARTS at least twice per IRQ. --Brett
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