From owner-freebsd-hackers Sun Feb 4 23:30:26 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id XAA08715 for hackers-outgoing; Sun, 4 Feb 1996 23:30:26 -0800 (PST) Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id XAA08709 for ; Sun, 4 Feb 1996 23:30:22 -0800 (PST) Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id IAA20098; Mon, 5 Feb 1996 08:30:27 +0100 From: Luigi Rizzo Message-Id: <199602050730.IAA20098@labinfo.iet.unipi.it> Subject: Re: FAT filesystem performance To: joerg_wunsch@uriah.heep.sax.de Date: Mon, 5 Feb 1996 08:30:26 +0100 (MET) Cc: freebsd-hackers@FreeBSD.org In-Reply-To: <199602050135.CAA02717@uriah.heep.sax.de> from "J Wunsch" at Feb 5, 96 02:35:16 am X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-hackers@FreeBSD.org Precedence: bulk > > 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. I was talking about regular files. > 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. A high performance FAT filesystem is certainly useful, but it might require a lot of work. Given that some people is now looking at the stability of the FAT filesystem, I was trying to understand if there is something simple that can be done to improve performance at a reasonable cost. More thoughts on high performance FAT will follow in a separate message. Luigi ==================================================================== Luigi Rizzo Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it Universita' di Pisa tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 http://www.iet.unipi.it/~luigi/ ====================================================================