From owner-freebsd-hackers Sun Feb 4 22:17:48 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id WAA05148 for hackers-outgoing; Sun, 4 Feb 1996 22:17:48 -0800 (PST) Received: from eac.iafrica.com (slipper119226.iafrica.com [196.7.119.226]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id WAA05141 for ; Sun, 4 Feb 1996 22:17:42 -0800 (PST) Received: (from rnordier@localhost) by eac.iafrica.com (8.6.12/8.6.12) id IAA03554 for hackers@freebsd.org; Mon, 5 Feb 1996 08:16:28 +0200 From: Robert Nordier Message-Id: <199602050616.IAA03554@eac.iafrica.com> Subject: Re: FAT filesystem performance To: hackers@freebsd.org Date: Mon, 5 Feb 1996 08:16:27 +0200 (SAT) In-Reply-To: <199602050350.IAA24118@hq.icb.chel.su> from "Serge A. Babkin" at Feb 5, 96 08:50:19 am X-Mailer: ELM [version 2.4 PL24 ME8a] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hackers@freebsd.org Precedence: bulk On Mon, 5 Jan 1996, Serge A. Babkin wrote: > > The FAT-caching in the MACH implementation (you *could* just port the > > MACH code...) takes a significant amount of memory, IMO. > > Hmm... FAT can contain at most 64K of entries, each 2 bytes long, so > the needed amount of memory (if you cache raw FAT and don't try to make > any ``cooked'' version) must be at most 128Kbytes long. IMHO the raw FAT > is enough convenient ant takes not very much of memory. Agreed. This is what the original author of the MS-DOS filesystem had to say on the subject of caching: The new MS-DOS [ie. DOS 2.0] does not keep the file allocation tables in memory at all times. Instead the tables share the use of sector buffers.... This change in the DOS goes completely against my original design principles.... Now we're back to doing disk reads just to find out where the data is. -- Tim Paterson, Byte, June 1983. -- Robert Nordier