Date: Tue, 26 May 1998 12:14:22 -0500 (EST) From: "John S. Dyson" <toor@dyson.iquest.net> To: luigi@labinfo.iet.unipi.it (Luigi Rizzo) Cc: dwmalone@maths.tcd.ie, dag-erli@ifi.uio.no, robert+freebsd@cyrus.watson.org, stable@FreeBSD.ORG Subject: Re: vnconfig + swap with sparse files Message-ID: <199805261714.MAA20027@dyson.iquest.net> In-Reply-To: <199805261116.NAA21948@labinfo.iet.unipi.it> from Luigi Rizzo at "May 26, 98 01:16:15 pm"
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> > > A sparse file cannot possibly work as swap since it does not have any > > > space allocate to it on the disk, and you *want* to allocate space on > > > the disk - where else are you going to swap out your data? > > > > Actually - it will work if you are swaping over NFS, (or at least did > > the last time I made swap files for our xterminals). Though I admit > > this is quite different. > > if i remember well there was a problem with sparse files and nfs as > well, and it was related to block sizes. > > My understanding of the problem was the following: > > If the swapper has to save only one page (4K) and the NFS blocksize > is 8K, the process involves reading an 8K block from the file, > "updating" the 4K half of interest, and writing back to the file. The > first read might return some kind of notification that the page did not > exist and somehow this caused problems. > > I may be totally wrong, or the problem might have been fixed (or it > could be fixed using 4K NFS blocks) > That code is a nightmare, and needs work. It might be better in -current, but is still a mess. John To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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