From owner-freebsd-current Fri Oct 9 02:11:11 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id CAA25304 for freebsd-current-outgoing; Fri, 9 Oct 1998 02:11:11 -0700 (PDT) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from mail.ftf.dk (mail.ftf.net [129.142.64.2]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id CAA25299 for ; Fri, 9 Oct 1998 02:11:04 -0700 (PDT) (envelope-from regnauld@deepo.prosa.dk) Received: from mail.prosa.dk ([192.168.100.254]) by mail.ftf.dk (8.8.8/8.8.8/gw-ftf-1.0) with ESMTP id LAA20379; Fri, 9 Oct 1998 11:16:06 +0200 (CEST) (envelope-from regnauld@deepo.prosa.dk) X-Authentication-Warning: mail.ftf.dk: Host [192.168.100.254] claimed to be mail.prosa.dk Received: from deepo.prosa.dk (deepo.prosa.dk [192.168.100.10]) by mail.prosa.dk (8.8.8/8.8.5/prosa-1.1) with ESMTP id LAA10461; Fri, 9 Oct 1998 11:29:34 +0200 (CEST) Received: (from regnauld@localhost) by deepo.prosa.dk (8.8.8/8.8.5/prosa-1.1) id LAA09741; Fri, 9 Oct 1998 11:21:54 +0200 (CEST) Message-ID: <19981009112154.45808@deepo.prosa.dk> Date: Fri, 9 Oct 1998 11:21:54 +0200 From: Philippe Regnauld To: Marius Bendiksen Cc: freebsd-current@FreeBSD.ORG Subject: Re: CDROM as system disk References: <199810081905.MAA26707@usr08.primenet.com> <3.0.5.32.19981009083720.00929a20@mail.scancall.no> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Mailer: Mutt 0.88e In-Reply-To: <3.0.5.32.19981009083720.00929a20@mail.scancall.no>; from Marius Bendiksen on Fri, Oct 09, 1998 at 08:37:20AM +0200 X-Operating-System: FreeBSD 2.2.6-RELEASE i386 Phone: +45 3336 4148 Address: Ahlefeldtsgade 16, 1359 Copenhagen K, Denmark Organization: PROSA Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Marius Bendiksen writes: > >Slight problem, disk caching. If you are going to ping the drive every N > >time units as a 'keep-alive', those blocks will very quickly get cached; > >unless you devise some clever algorithm that will always ensure that you > >get a block not in the cache (consider the cache could me a megabyte or > >more in size, and this gets tricky) > > So, we'll need some function to flush the cache, or do uncached i/o... We're talking about the CD-ROM's own cache. It's likely you can't disable it on cheapo IDE models (some IDE guru prove me wrong-- Søren ?), so you'll need to do like mentioned before: read random blocks, _and stop doing that while you're doing "legitimate" I/O_ (that means probably hacking the driver in some way, with a timer). -- -[ Philippe Regnauld / sysadmin / regnauld@deepo.prosa.dk / +55.4N +11.3E ]- The Internet is busy. Please try again later. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message