Date: Tue, 26 May 1998 13:16:15 +0200 (MET DST) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: dwmalone@maths.tcd.ie (David Malone) Cc: dag-erli@ifi.uio.no, robert+freebsd@cyrus.watson.org, stable@FreeBSD.ORG Subject: Re: vnconfig + swap with sparse files Message-ID: <199805261116.NAA21948@labinfo.iet.unipi.it> In-Reply-To: <9805261327.aa21737@salmon.maths.tcd.ie> from "David Malone" at May 26, 98 01:26:39 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) cheers 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/ _____________________________|______________________________________ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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