From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Subject: Re: KVM "fake DAX" device flushing Date: Thu, 11 May 2017 12:15:43 -0700 Message-ID: References: <1494431760-6455-1-git-send-email-pagupta@redhat.com> <20170511181703.GC8701@stefanha-x1.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: Pankaj Gupta , KVM list , qemu-devel@nongnu.org, Rik van Riel , Paolo Bonzini , kwolf@redhat.com, Haozhong Zhang , Xiao Guangrong To: Stefan Hajnoczi Return-path: Received: from mail-oi0-f48.google.com ([209.85.218.48]:36440 "EHLO mail-oi0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753308AbdEKTPo (ORCPT ); Thu, 11 May 2017 15:15:44 -0400 Received: by mail-oi0-f48.google.com with SMTP id h4so41947538oib.3 for ; Thu, 11 May 2017 12:15:44 -0700 (PDT) In-Reply-To: <20170511181703.GC8701@stefanha-x1.localdomain> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, May 11, 2017 at 11:17 AM, Stefan Hajnoczi wrote: > On Wed, May 10, 2017 at 09:26:00PM +0530, Pankaj Gupta wrote: >> We are sharing initial project proposal for >> 'KVM "fake DAX" device flushing' project for feedback. >> Got the idea during discussion with 'Rik van Riel'. > > CCing NVDIMM folks. > >> >> Also, request answers to 'Questions' section. >> >> Abstract : >> ---------- >> Project idea is to use fake persistent memory with direct >> access(DAX) in virtual machines. Overall goal of project >> is to increase the number of virtual machines that can be >> run on a physical machine, in order to increase the density >> of customer virtual machines. >> >> The idea is to avoid the guest page cache, and minimize the >> memory footprint of virtual machines. By presenting a disk >> image as a nvdimm direct access (DAX) memory region in a >> virtual machine, the guest OS can avoid using page cache >> memory for most file accesses. How is this different than the solution that Clear Containers came up with? https://lwn.net/Articles/644675/ From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36950) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d8tYy-0000Qd-PC for qemu-devel@nongnu.org; Thu, 11 May 2017 15:15:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d8tYx-0004oa-C4 for qemu-devel@nongnu.org; Thu, 11 May 2017 15:15:48 -0400 Received: from mail-oi0-x22b.google.com ([2607:f8b0:4003:c06::22b]:34013) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1d8tYx-0004mA-5e for qemu-devel@nongnu.org; Thu, 11 May 2017 15:15:47 -0400 Received: by mail-oi0-x22b.google.com with SMTP id b204so42125566oii.1 for ; Thu, 11 May 2017 12:15:44 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20170511181703.GC8701@stefanha-x1.localdomain> References: <1494431760-6455-1-git-send-email-pagupta@redhat.com> <20170511181703.GC8701@stefanha-x1.localdomain> From: Dan Williams Date: Thu, 11 May 2017 12:15:43 -0700 Message-ID: Content-Type: text/plain; charset="UTF-8" Subject: Re: [Qemu-devel] KVM "fake DAX" device flushing List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Pankaj Gupta , KVM list , qemu-devel@nongnu.org, Rik van Riel , Paolo Bonzini , kwolf@redhat.com, Haozhong Zhang , Xiao Guangrong On Thu, May 11, 2017 at 11:17 AM, Stefan Hajnoczi wrote: > On Wed, May 10, 2017 at 09:26:00PM +0530, Pankaj Gupta wrote: >> We are sharing initial project proposal for >> 'KVM "fake DAX" device flushing' project for feedback. >> Got the idea during discussion with 'Rik van Riel'. > > CCing NVDIMM folks. > >> >> Also, request answers to 'Questions' section. >> >> Abstract : >> ---------- >> Project idea is to use fake persistent memory with direct >> access(DAX) in virtual machines. Overall goal of project >> is to increase the number of virtual machines that can be >> run on a physical machine, in order to increase the density >> of customer virtual machines. >> >> The idea is to avoid the guest page cache, and minimize the >> memory footprint of virtual machines. By presenting a disk >> image as a nvdimm direct access (DAX) memory region in a >> virtual machine, the guest OS can avoid using page cache >> memory for most file accesses. How is this different than the solution that Clear Containers came up with? https://lwn.net/Articles/644675/