From owner-freebsd-hackers Sun Feb 4 17:50:06 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id RAA21774 for hackers-outgoing; Sun, 4 Feb 1996 17:50:06 -0800 (PST) Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id RAA21730 for ; Sun, 4 Feb 1996 17:49:58 -0800 (PST) Received: from sax.sax.de by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id CAA12933 for ; Mon, 5 Feb 1996 02:49:50 +0100 Received: by sax.sax.de (8.6.11/8.6.12-s1) with UUCP id CAA05229 for freebsd-hackers@freebsd.org; Mon, 5 Feb 1996 02:49:49 +0100 Received: (from j@localhost) by uriah.heep.sax.de (8.7.3/8.6.9) id CAA02717 for freebsd-hackers@freebsd.org; Mon, 5 Feb 1996 02:35:36 +0100 (MET) From: J Wunsch Message-Id: <199602050135.CAA02717@uriah.heep.sax.de> Subject: Re: FAT filesystem performance To: freebsd-hackers@freebsd.org (FreeBSD hackers) Date: Mon, 5 Feb 1996 02:35:35 +0100 (MET) Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) In-Reply-To: <199602042218.XAA19281@labinfo.iet.unipi.it> from "Luigi Rizzo" at Feb 4, 96 11:18:18 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 Sender: owner-hackers@freebsd.org Precedence: bulk As Luigi Rizzo wrote: > > > This would only shift the problem from the msdosfs code into the > > various device drivers. > > Well, let me first say that I don't know exactly how mmapping files > works internally. But what I expect is to have the kernel do its > best to keep blocks in core and write them back (if necessary) when > the file is unmapped. That is also true for any regular file. If you wanna improve the FAT file system implementation, first study its bottlenecks. The msdosfs code could certainly be improved in terms of robustness and performance. Since it's kernel-level, it has full control over what kind of buffers it will allocate, either pageable or non-pageable. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)