Date: Sun, 12 Jan 2003 13:11:12 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: David Schultz <dschultz@uclink.Berkeley.EDU> Cc: Tomas Pluskal <plusik@pohoda.cz>, Bruce Evans <bde@zeta.org.au>, freebsd-fs@FreeBSD.ORG Subject: Re: seeking help to rewrite the msdos filesystem Message-ID: <3E21D9F0.A2AA9F0@mindspring.com> References: <20021114020947.O6495-100000@gamplex.bde.org> <20030111191832.B18312-200000@localhost.localdomain> <20030112154753.GA3284@HAL9000.homeunix.com>
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David Schultz wrote: [ ... clustering patch ... ] > I'm not sure I understand what you're trying to do here. Does > this work with files that are fragmented? You appear to be > assuming that they are not. Maybe you copied the code from the > cd9660 filesystem, which does not permit external fragmentation. > I think you need to use the cluster number returned by pcbmap() to > index into the FAT and extract the next cluster number, repeating > until you find that the next cluster is not contiguous, or until > you hit MAXBSIZE or the end of the file. FWIW, I had the same question, but I haven't had time to really stare at some FS instances from a working Windows box from the FreeBSD side of things, to know how bad this really is, so I thought that this might be on purpose. I don't expect he'd ever see it at all, given his intended usage. I think that it's not that bad (really), but will lose about 50% of the performance improvement on a file that's partially fragged, but still contains contiguous blocks in it. On a generally fragged file, you're not going to trigger the code at all. I'm not really sure a cluster can start at a non-boundary, anyway (this is what I need to looks at examples to see), so it may be a total non-issue. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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