From owner-freebsd-hackers Wed Jul 17 11:31:55 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id LAA08946 for hackers-outgoing; Wed, 17 Jul 1996 11:31:55 -0700 (PDT) Received: from schubert.promo.de (schubert.Promo.DE [194.45.188.65]) by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id LAA08940 for ; Wed, 17 Jul 1996 11:31:49 -0700 (PDT) Received: from quick.promo.de (quick.Promo.DE [194.45.188.67]) by schubert.promo.de (8.6.12/8.6.12) with SMTP id UAA05901; Wed, 17 Jul 1996 20:29:41 +0200 Message-ID: Date: 17 Jul 1996 20:29:19 +0200 From: "Stefan Bethke" Subject: Re: mitsumi CD-ROM To: "Dennis" Cc: hackers@freebsd.org X-Mailer: Mail*Link SMTP-QM 3.0.2 Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; Name="Message Body" Content-Transfer-Encoding: quoted-printable Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk > stealing the bus is stealing the cpu when a router is doing largely > transfers from cards. Your cant process packets until you get them. And = if > the cpu is in a transfer cycle and cant get the bus then its idle. > > I dont want my packet transfers being interrupted by trivial disk = activity. > An IDE will only use the CPU when it has it already anyway.....a > bus-master makes the system much less predictable and assumes the wrong > priorities. The priorities are independent of whether programmed IO or bus-mastering = is used; if a disk controller has the higher priority, it will interrupt = a network controller regardless. If I understand you correctly, you want the disk controller only to = consume resources when there is no network activity; I'm not too familiar = with PCI's or FBSD's arbitration logic, but I assume that FBSD will try = to service disk controllers before network controllers (please correct me = on this). I'm sure one could change that with some effort to give the nic = the higher priority. However, if you're intention is to really make this one router forward = packets with lower latency, you might want to try to run it completely = off MFS; then there will be no disk activity at all. Stefan