From owner-freebsd-current Tue Aug 31 14: 6:25 1999 Delivered-To: freebsd-current@freebsd.org Received: from mail.rdc2.on.home.com (ha1.rdc2.on.home.com [24.9.0.15]) by hub.freebsd.org (Postfix) with ESMTP id 7B0AD14D5E for ; Tue, 31 Aug 1999 14:06:21 -0700 (PDT) (envelope-from street@iname.com) Received: from mired.eh.local ([24.64.136.188]) by mail.rdc2.on.home.com (InterMail v4.01.01.07 201-229-111-110) with ESMTP id <19990831210532.RJWA5161.mail.rdc2.on.home.com@mired.eh.local>; Tue, 31 Aug 1999 14:05:32 -0700 Received: (from kws@localhost) by mired.eh.local (8.9.3/8.9.3) id RAA02551; Tue, 31 Aug 1999 17:05:32 -0400 (EDT) (envelope-from kws) From: Kevin Street MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <14284.17307.842265.468860@mired.eh.local> Date: Tue, 31 Aug 1999 17:05:31 -0400 (EDT) To: Soren Schmidt Cc: current@FreeBSD.ORG Subject: Re: HEADS UP! ATA driver (atapi DMA).. In-Reply-To: <199908311952.VAA80929@freebsd.dk> References: <87btbnetgc.fsf@mired.eh.local> <199908311952.VAA80929@freebsd.dk> X-Mailer: VM 6.71 under 21.1 "20 Minutes to Nikko" XEmacs Lucid (patch 2) Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Soren Schmidt writes: >Depends.. There are many factors involved here, using DMA only lowers >the CPU usage, and will enable faster transfers if the problem was >that the CPU was saturated with the PIO transfer. It gave about >double the transfer rate on my old P6 based maschine, because the >CPU drain was the limitting factor. Most modern CDROM are variable >speed, and you will see varying rates depending on the quality of >the media. dd'ing the whole cd and watching with iostat shows speeds from 2M increasing to 5.5M on the outside tracks with cpu staying at 98% to 100% idle on a PII 400. So DMA seems to be doing its stuff. I did try checking for correct data coming off the cd as well, and saw no problems. -- Kevin Street street@iname.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message