From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3CC45C71122 for ; Sat, 13 Oct 2018 16:06:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02BCD206B2 for ; Sat, 13 Oct 2018 16:06:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="hDGEHqrg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 02BCD206B2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726697AbeJMXoB (ORCPT ); Sat, 13 Oct 2018 19:44:01 -0400 Received: from mail-ot1-f65.google.com ([209.85.210.65]:35918 "EHLO mail-ot1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726329AbeJMXoA (ORCPT ); Sat, 13 Oct 2018 19:44:00 -0400 Received: by mail-ot1-f65.google.com with SMTP id x4so13742407otg.3 for ; Sat, 13 Oct 2018 09:06:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=cSy8aZNbc+Fp01O7mr7iurX03QUJ9OJYlQTrAqkvWPw=; b=hDGEHqrgK4JSJfehJqv2wXlWnet/OGIHzcUE3UOm0uULgIRbkjOJmYaKaXeiRvwa0s 86kuBoD+TNbeKTHvMIsa7UuuAWHucbuhj7azuQIBTwAX4kSCQeKQiPN53a6X/dt4lmfo 1uxMrGVYgojBA3jzUxilsidTGChVg4XJm8pnqOP7Z8aAKMF2nAcnjqVN0dzEItcL/Vr+ PcLpNw3rkruXvBC65QhQbQ8MupdIy8e8nO4XtDTH69LLLbVxrXx4cQU8ZYoxl+YK8U3P NgONb0vL+sS+zCrWaDQ9cYtgfiztgX/hmylGsFIVD0rG7lGvDeu9Fg/i4DjSMFtIyjE9 LV6g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cSy8aZNbc+Fp01O7mr7iurX03QUJ9OJYlQTrAqkvWPw=; b=VNOCYZ5ZoH+vcud9Y8ZMZPlBd1njk7Jk97dot6bkk1WwksHjcRxU8NobRfrwaL0nR8 5VGOWCwS7z1vplqXKs/O9IyM3X62/kAjWYY4kkLXBE0q3ITJ3qJs4tmtPM2OWK3eUXCl mib4omCWLqije3OZ3+ei7k0V4NedVNQtDIYBS1EKppRNeoftwQE76vzaP+mBr/AIfzsl RzmOljXrg71Z8rnbeAd03rERmbl2OevD6tMrkxRHngtLF+ZSl+/2KkwfY1Y8rt5oLikU R3rsbSmrBpf+mu2yFQ41+taRygiowNtsPS4Mz1vHZQURpoleKjBMtKr3fKKlxZoTIsDg aoCg== X-Gm-Message-State: ABuFfoi1Tma27woWjbjzJqee97qXgXOl6r3RyPEIq8OgajBAYzCmpHRf QHOhpQ++XzLn7ORDaRkPDLcHjC6C/6ckQ+ZCRK/JVA== X-Google-Smtp-Source: ACcGV61+6NRZBHTaiFPGRH1TESsnwhHDwWtzvsoWrQ3EkoGniQ7N5R2WTV3014lMC/rNJ3q4U3pDJ5boaYucGeZWenE= X-Received: by 2002:a9d:758f:: with SMTP id s15mr6414736otk.353.1539446778225; Sat, 13 Oct 2018 09:06:18 -0700 (PDT) MIME-Version: 1.0 References: <20181013050021.11962-1-pagupta@redhat.com> In-Reply-To: <20181013050021.11962-1-pagupta@redhat.com> From: Dan Williams Date: Sat, 13 Oct 2018 09:06:07 -0700 Message-ID: Subject: Re: [PATCH v2 0/2] kvm "fake DAX" device To: Pankaj Gupta Cc: Linux Kernel Mailing List , KVM list , Qemu Developers , linux-nvdimm , Jan Kara , Stefan Hajnoczi , Rik van Riel , Nitesh Narayan Lal , Kevin Wolf , Paolo Bonzini , zwisler@kernel.org, Vishal L Verma , Dave Jiang , David Hildenbrand , Xiao Guangrong , Christoph Hellwig , "Michael S. Tsirkin" , lcapitulino@redhat.com, Igor Mammedov , Eric Blake Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 12, 2018 at 10:00 PM Pankaj Gupta wrote: > > This patch series has implementation for "fake DAX". > "fake DAX" is fake persistent memory(nvdimm) in guest > which allows to bypass the guest page cache. This also > implements a VIRTIO based asynchronous flush mechanism. Can we stop calling this 'fake DAX', because it isn't 'DAX' and it's starting to confuse people. This enabling is effectively a host-page-cache-passthrough mechanism not DAX. Let's call the whole approach virtio-pmem, and leave DAX out of the name to hopefully prevent people from wondering why some DAX features are disabled with this driver. For example MAP_SYNC is not compatible with this approach. Additional enabling is need to disable MAP_SYNC in the presence of a virtio-pmem device. See the rough proposal here: https://lkml.org/lkml/2018/4/25/756