From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 20 Jan 2001 18:53:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 20 Jan 2001 18:52:53 -0500 Received: from mserv1c.vianw.co.uk ([195.102.240.33]:47572 "EHLO mserv1c.vianw.co.uk") by vger.kernel.org with ESMTP id ; Sat, 20 Jan 2001 18:52:48 -0500 From: Alan Chandler To: linux-kernel@vger.kernel.org Subject: Re: [preview] Latest AMD & VIA IDE drivers with UDMA100 support Date: Sat, 20 Jan 2001 23:55:13 +0000 Organization: [private individual] Message-ID: In-Reply-To: <20010120215641.A1818@suse.cz> In-Reply-To: X-Mailer: Forte Agent 1.8/32.548 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 20 Jan 2001 14:57:07 -0800 (PST), Andre Hedrick wrote: ... > >Vojtech, I worry that the dynamic timing that you are calculating could >bite you. Timings are exact especially at modes 3/4/5 the margins go to >an effective zero for varition or wiggle room. The state diagrams from >Quantum that created the Ultra DMA 0,1,2,3,4,5 show how darn tight it >constrained. You need to assume absolutes because the various board >makers screw up the skew tables by the PCB lane traces. > I am not sure this is just a question of small variations. The hdparm -t differences between these two versions is quite significant. This evidence would imply that the two approaches are making fundemental different decisions about what my hardware can do! Under 2.2.17 /dev/hda: Timing buffered disk reads: 64 MB in 21.86 seconds = 2.93 MB/sec /dev/hdc: Timing buffered disk reads: 64 MB in 20.81 seconds = 3.08 MB/sec Under 2.4.0 /dev/hda: Timing buffered disk reads: 64 MB in 6.58 seconds = 9.73 MB/sec /dev/hdc: Timing buffered disk reads: 64 MB in 6.59 seconds = 9.71 MB/sec Alan alan@chandlerfamily.org.uk http://www.chandler.u-net.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/