From owner-freebsd-hackers Tue Sep 12 08:21:41 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id IAA14880 for hackers-outgoing; Tue, 12 Sep 1995 08:21:41 -0700 Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.6.12/8.6.6) with ESMTP id IAA14872 for ; Tue, 12 Sep 1995 08:21:33 -0700 Received: from sax.sax.de by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id RAA28353 for ; Tue, 12 Sep 1995 17:21:28 +0200 Received: by sax.sax.de (8.6.11/8.6.12-s1) with UUCP id RAA07644 for hackers@freebsd.org; Tue, 12 Sep 1995 17:21:28 +0200 Received: (from j@localhost) by uriah.heep.sax.de (8.6.12/8.6.9) id NAA29200 for hackers@freebsd.org; Tue, 12 Sep 1995 13:54:10 +0200 From: J Wunsch Message-Id: <199509121154.NAA29200@uriah.heep.sax.de> Subject: Re: higher density diskettes To: hackers@freebsd.org Date: Tue, 12 Sep 1995 13:54:10 +0200 (MET DST) Reply-To: hackers@freebsd.org In-Reply-To: <199509120758.RAA15898@godzilla.zeta.org.au> from "Bruce Evans" at Sep 12, 95 05:58:58 pm X-Phone: +49-351-2012 669 X-Mailer: ELM [version 2.4 PL23] MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Content-Length: 724 Sender: hackers-owner@freebsd.org Precedence: bulk As Bruce Evans wrote: > > ... The FreeBSD driver uses a head > settle delay of hz/16 ticks, i.e., between 50 and 60 ms. This is much > longer than necessary. I think the spec is 15 msec. The spec suffers from a lack of reality. We've once had hz/32, and got (too) many problem reports. That's why the more conservative value has been used. I know that the existing driver is not at the end of optimization, but i'm not sure whether a potential gain of 25 % or less in speed would be worth the effort. People usually only recognize speed changes by a factor of 2 or more. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ Never trust an operating system you don't have sources for. ;-)