From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Olszewski Subject: Avoiding the page cache? Date: Thu, 28 Jan 2010 16:38:14 -0500 Message-ID: <4B6203C6.90907@csail.mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from DMZ-MAILSEC-SCANNER-6.MIT.EDU ([18.7.68.35]:42655 "EHLO dmz-mailsec-scanner-6.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752620Ab0A1VnR (ORCPT ); Thu, 28 Jan 2010 16:43:17 -0500 Received: from outgoing.mit.edu (OUTGOING-AUTH.MIT.EDU [18.7.22.103]) by biscayne-one-station.mit.edu (8.13.6/8.9.2) with ESMTP id o0SLbNtc003883 for ; Thu, 28 Jan 2010 16:37:24 -0500 (EST) Received: from deadlock.csail.mit.edu (deadlock.csail.mit.edu [128.30.64.23]) (authenticated bits=0) (User authenticated as mareko@CSAIL.MIT.EDU@ATHENA.MIT.EDU) by outgoing.mit.edu (8.13.6/8.12.4) with ESMTP id o0SLcWT3028469 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Thu, 28 Jan 2010 16:38:33 -0500 (EST) Sender: kvm-owner@vger.kernel.org List-ID: Hello, I'm trying to start using kvm to do some research here at MIT. I would like to try out some interesting page mapping ideas we have that would be easier to try out in a hypervisor than inside the linux kernel. However, I would like to start hacking a simple version of kvm that doesn't do any shadow page table caching as this would make things much easier. I noticed that some earlier versions of kvm in the mainline kernel repository (eg 399badf315bd...) around January 2007 do this, but I had trouble getting them to work with qemu on an x86_64 processor (seems like x86_64 was not supported that well in the kvm branch of qemu back then). How hard do you guys think in would be to change the current code to avoid using the cache? I'm guessing I would have to change mmu_free_roots() to free all the pages in the shadow page table, but beyond that I'm a bit lost. Can anybody help me out with some small pointers to get me started? Thanks! Marek