From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Vivier Subject: Re: file-backed guest memory Date: Thu, 12 Apr 2007 17:47:35 +0200 Message-ID: <461E5497.3090409@bull.net> References: <461E5181.6010504@mr511.de> <461E5286.7090100@qumranet.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1020865868==" Cc: kvm-devel To: Avi Kivity Return-path: In-Reply-To: <461E5286.7090100-atKUWr5tajBWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --===============1020865868== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig3C81D053F33772D0E638B4C3" This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig3C81D053F33772D0E638B4C3 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Avi Kivity wrote: > Michael Riepe wrote: >> Hi! >> >> This is just a (probably silly) idea I had the other day. Currently, t= he >> guest's memory is allocated inside the kernel and exported to userspac= e >> via mmap(). But wouldn't it also be possible to create a file in >> userspace and pass its descriptor to kvm? If we also pass file offset >> and length parameters for each memslot, all segments can (but need not= ) >> reside in the same file. There would be a persistent snapshot of the >> VM's physical memory, and it would enable the VM to page out the guest= 's >> pages. One could also do strange things like mapping a portion of the >> file several times, e.g. to emulate an architecture with incomplete >> address decoding. Applications that absolutely want to use anonymous >> memory could pass -1 as the fd, as they do with mmap(MAP_ANONYMOUS). >> =20 >=20 > Arnd suggested this way back when kvm was first posted on lkml, and I=20 > agree that this is a very useful mechanism. You get on-demand loading,= =20 > swap, hugetlbfs, and maybe other nifty stuff. I think I know how to do= =20 > this for the current mmu, but I'm worried that it will have a=20 > performance impact with the nested page tables mmu. >=20 Perhaps you could use code from kqemu ? Regards, Laurent --=20 ------------- Laurent.Vivier-6ktuUTfB/bM@public.gmane.org -------------- "Any sufficiently advanced technology is indistinguishable from magic." - Arthur C. Clarke --------------enig3C81D053F33772D0E638B4C3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.7 (GNU/Linux) iD8DBQFGHlSd9Kffa9pFVzwRAn7bAKDbrghxFuuaUJeEmI5Rf05Ih3ThEgCdEeEf Nr8rY/dOrW1FEI7hFgVmY3g= =EMdN -----END PGP SIGNATURE----- --------------enig3C81D053F33772D0E638B4C3-- --===============1020865868== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV --===============1020865868== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ kvm-devel mailing list kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org https://lists.sourceforge.net/lists/listinfo/kvm-devel --===============1020865868==--