Date: Tue, 8 Oct 2002 00:06:56 +0200 From: Wilko Bulte <wkb@freebie.xs4all.nl> To: Terry Lambert <tlambert2@mindspring.com> Cc: Peter Wemm <peter@wemm.org>, Mikhail Teterin <mi+mx@aldan.algebra.com>, arch@FreeBSD.ORG Subject: Re: swapon some regular file Message-ID: <20021008000656.A598@freebie.xs4all.nl> In-Reply-To: <3DA204A7.50530BE5@mindspring.com>; from tlambert2@mindspring.com on Mon, Oct 07, 2002 at 03:03:19PM -0700 References: <20021007212545.C363B2A88D@canning.wemm.org> <3DA204A7.50530BE5@mindspring.com>
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On Mon, Oct 07, 2002 at 03:03:19PM -0700, Terry Lambert wrote: > Peter Wemm wrote: > > > Users wishing to swap onto a local regular file have to go through the > > > vnconfig/mdconfig gimnastics. Is that intentional? > > > > Yes, it is quite intentional. swap_pager doesn't have the code to do > > logical to physical translation that file IO would require. And the > > VOP_BMAP calls that do that add new complications, including an additional > > place it can sleep or run out of memory. > > > > We can get away with it for swapping to a file over NFS because the remote > > server does the translation, not us. > > > > In reality, what is required is some careful cut/paste of code from > > vnode_pager to swap_pager to add the missing bits, and some care to deal > > with the complications. > > > > vnconfig/mdconfig work because that basically adds the logical -> physical > > translation step. I'd just as soon not have to mess with this though. > > It would be useful to be able to ask a file for its list of > physical blocks on the underlying device, so that you could > sort them into contiguous extents, and then use *those*, > instead of eating the translation overhead, each time... Sounds a bit like VMS (IIRC..) :) -- | / o / /_ _ wilko@FreeBSD.org |/|/ / / /( (_) Bulte Arnhem, the Netherlands To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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