From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764800AbXGYNZX (ORCPT ); Wed, 25 Jul 2007 09:25:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753590AbXGYNZL (ORCPT ); Wed, 25 Jul 2007 09:25:11 -0400 Received: from il.qumranet.com ([82.166.9.18]:38611 "EHLO il.qumranet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750944AbXGYNZK (ORCPT ); Wed, 25 Jul 2007 09:25:10 -0400 Message-ID: <46A74F34.5040508@qumranet.com> Date: Wed, 25 Jul 2007 16:25:08 +0300 From: Avi Kivity User-Agent: Thunderbird 2.0.0.4 (X11/20070615) MIME-Version: 1.0 To: Shaohua Li CC: kvm-devel , lkml Subject: Re: [kvm-devel] [RFC 7/8]KVM: swap out guest pages References: <1185173505.2645.71.camel@sli10-conroe.sh.intel.com> <46A612C8.6090804@qumranet.com> <288dbef70707250455p656b09cft20ebc7a013e8a76f@mail.gmail.com> <288dbef70707250620u5483d5dbxbcc461f8f685acdc@mail.gmail.com> In-Reply-To: <288dbef70707250620u5483d5dbxbcc461f8f685acdc@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (firebolt.argo.co.il [0.0.0.0]); Wed, 25 Jul 2007 16:25:08 +0300 (IDT) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Shaohua Li wrote: >> So write to a file, right? Yes, it can avoid use move to swap, and >> should be feasible. > Say you want to write guest pages out to file A of back store fs, in > kvm->writepage(), we could do: > 1. lower_page = grap_cache_page(file A's mapping) > 2. file A's ->prepare_write(lower_page) > 3. copy kvm guest page to lower_page > 4. file A's ->commit_write(lower_page) > then guest page can be freed. Just like the stack fs does. The > downside is step 1 needs allocate a new page. Yeah. Hopefully we can find a better solution, the copy isn't pretty (though it's probably not too bad from a performance point of view compared to the IPIs involved). -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.