Date: Mon, 5 Feb 1996 08:50:19 +0500 (GMT+0500) From: "Serge A. Babkin" <babkin@hq.icb.chel.su> To: terry@lambert.org (Terry Lambert) Cc: luigi@labinfo.iet.unipi.it, hackers@FreeBSD.org Subject: Re: FAT filesystem performance Message-ID: <199602050350.IAA24118@hq.icb.chel.su> In-Reply-To: <199602042148.OAA06143@phaeton.artisoft.com> from "Terry Lambert" at Feb 4, 96 02:48:27 pm
next in thread | previous in thread | raw e-mail | index | archive | help
> > We use FAT filesystems both in the kernel, and in mtools. > > For the latter, I thought there was a quick fix to the problem of > > caching the FAT: just mmap the device, and the kernel will do caching > > for you. Well, it does not look that simple, as the vast majority of > > raw devices does not support mmap. > > > > I am wondering: how hard would it be to add mmap() to, say, wd.c ? > > Would it have other useful applications ? > > This would be useful for mtools, but not for the kernel version of FAT. > > 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. -SB
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199602050350.IAA24118>