From owner-freebsd-arch Mon Oct 7 14:26: 3 2002 Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9365237B407 for ; Mon, 7 Oct 2002 14:25:59 -0700 (PDT) Received: from canning.wemm.org (canning.wemm.org [192.203.228.65]) by mx1.FreeBSD.org (Postfix) with ESMTP id E469B43E6A for ; Mon, 7 Oct 2002 14:25:55 -0700 (PDT) (envelope-from peter@wemm.org) Received: from wemm.org (localhost [127.0.0.1]) by canning.wemm.org (Postfix) with ESMTP id C363B2A88D; Mon, 7 Oct 2002 14:25:45 -0700 (PDT) (envelope-from peter@wemm.org) X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 To: Mikhail Teterin Cc: arch@FreeBSD.org Subject: Re: swapon some regular file In-Reply-To: <200210071630.42512.mi+mx@aldan.algebra.com> Date: Mon, 07 Oct 2002 14:25:45 -0700 From: Peter Wemm Message-Id: <20021007212545.C363B2A88D@canning.wemm.org> Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Mikhail Teterin wrote: > Currently, swapon(2) will only succeed if the argument vn_isdisk(9), or > if it is an NFS-accessed file. > > 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. Cheers, -Peter -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message