From owner-freebsd-questions Tue Dec 24 12:01:09 1996 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.4/8.8.4) id MAA02478 for questions-outgoing; Tue, 24 Dec 1996 12:01:09 -0800 (PST) Received: from post-ofc01.srv.cis.pitt.edu (root@post-ofc01.srv.cis.pitt.edu [136.142.185.10]) by freefall.freebsd.org (8.8.4/8.8.4) with ESMTP id MAA02471 for ; Tue, 24 Dec 1996 12:01:05 -0800 (PST) Received: from unixs5.cis.pitt.edu (jddst19@unixs5.cis.pitt.edu [136.142.185.57]) by post-ofc01.srv.cis.pitt.edu with SMTP (8.8.3/cispo-2.0.1.7) ID ; Tue, 24 Dec 1996 15:00:31 -0500 (EST) Date: Tue, 24 Dec 1996 15:00:29 -0500 (EST) From: John D Duncan X-Sender: jddst19@unixs5.cis.pitt.edu To: Antonio Bemfica cc: freebsd-questions@freebsd.org Subject: Re: silo overflows In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-questions@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Silo overflows exist when the machine cannot retrieve data from the sio as fast as it is coming in, and so the UART sends a message to the kernel, and the kernel records the retry. possible causes of this problem are: A slow machine A heavily-loaded machine A 16450 UART chip on the serial line, which should be changed to a 16550A for unix A low priority to the sio servicing compiled into the kernel. An insanely high transfer rate set on cuaa1. I use an AMD 5x86 on a 486 motherboard, with a SIIG card that has 16550s on each line. My card was expensive to buy, and you can find a decent multi-function card or serial board that provides these chips for about 10-30 bucks. If you have these chips, and it's still slow, then you should find areas of processor-intense computing and stop using them when doing important serial work. The machine should be able to service the interrupts better when you are not compiling, etc. Netscape itself caused problems for me when I ran on 16450 uarts because of how processor-intensive it is. If you aren't doing work, upgrade your processor. If you have a fast processor, then there is a problem with your config. If you need to do work while running serial, lets say your machine is a combination news/ftp/ports server, and your processor is fast, then you should look into a high-performance serial card that gives you a much larger fifo on the uart. (fifo is the queue that the uart uses to fill with unserviced data.) there are boards with a meg or more of fifo memory on each line, or at least, there used to be.:) I think most basic fifos are 16-64k. the reason why the 16450 is slow is that it only has a couple of k on its buffer. I think it also has a poor block-transfer rate. I believe that there are also dma serial cards that avoid these problems well. there are a variety of options. But right now, I only get silo overflows when I am using several programs that use serial lines heavily, like ftp, news, and netscape. cheerio- John ============== jddst19+@pitt.edu John Duncan Freshman, University of Pittsburgh "I'm not a doctor, but I ate one at the UPMC..." On Mon, 23 Dec 1996, Antonio Bemfica wrote: > I keep getting the following message while doing ftp transfers (I connect > with user-ppp): > > /kernel: sio1: 1 more silo overflow (total xxx) > > The number (xxx) keeps growing ... Does anybody know why? > > Thanks > > Antonio > -- > |Antonio Bemfica -------------------------- bemfica@militzer.me.tuns.ca )) > |Halifax, Canada ------------------ http://militzer.me.tuns.ca/~bemfica (( > |this message has no cash value - valid only at participating locations )) > |not valid in combination with any other offer - sorry, no rain-checks (( >