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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 D3376C64E7B for ; Tue, 1 Dec 2020 11:07:03 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1FC2C206D8 for ; Tue, 1 Dec 2020 11:07:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="CdOY2C7S" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1FC2C206D8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:32956 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kk3Ur-0002bi-Vp for qemu-devel@archiver.kernel.org; Tue, 01 Dec 2020 06:07:02 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:47758) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kk3HZ-00038H-Ms for qemu-devel@nongnu.org; Tue, 01 Dec 2020 05:53:17 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:20748) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kk3HX-0001hB-Sr for qemu-devel@nongnu.org; Tue, 01 Dec 2020 05:53:17 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606819995; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Eu7lJn0aKflqPDi85Ziokul6w//LMkjmBVs6tEGTSRY=; b=CdOY2C7Si8ZkkG0V8Nna6vbG2egyyrdqcy40yqP9ZHM+BSiSxHnta9NLdouEOXAXkteaAw a8JlLYYfjkSiG+8H7xUuSVgDoyOBzIs3HEjcP642bfKfB21XxUuz6FJarSy3Vf0kvoglJg izOSySePgUelszkMRmdEjco3VaWzveI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-191-eOmWBz0XMyKzy49VhyfXuw-1; Tue, 01 Dec 2020 05:53:13 -0500 X-MC-Unique: eOmWBz0XMyKzy49VhyfXuw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5E17B817B92; Tue, 1 Dec 2020 10:53:12 +0000 (UTC) Received: from angien.pipo.sk (unknown [10.40.208.3]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C5F2119C47; Tue, 1 Dec 2020 10:53:03 +0000 (UTC) Date: Tue, 1 Dec 2020 11:53:00 +0100 From: Peter Krempa To: Andrey Gruzdev Subject: Re: [PATCH v4 0/6] UFFD write-tracking migration/snapshots Message-ID: <20201201105300.GQ105758@angien.pipo.sk> References: <20201126151734.743849-1-andrey.gruzdev@virtuozzo.com> <20201201070820.GO105758@angien.pipo.sk> MIME-Version: 1.0 In-Reply-To: X-PGP-Key-ID: 0xD018682B X-PGP-Key-Fingerprint: D294 FF38 A6A2 BF40 6C75 5DEF 36EC 16AC D018 682B User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pkrempa@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=pkrempa@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.496, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juan Quintela , Markus Armbruster , qemu-devel@nongnu.org, Peter Xu , "Dr . David Alan Gilbert" , Paolo Bonzini , Den Lunev Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Dec 01, 2020 at 11:42:18 +0300, Andrey Gruzdev wrote: > On 01.12.2020 10:08, Peter Krempa wrote: > > On Thu, Nov 26, 2020 at 18:17:28 +0300, Andrey Gruzdev via wrote: > > > This patch series is a kind of 'rethinking' of Denis Plotnikov's ideas he's [...] > > Note that in cases when qemu can't guarantee that the > > background_snapshot feature will work it should not advertise it. We > > need a way to check whether it's possible to use it, so we can replace > > the existing --live flag with it rather than adding a new one and > > shifting the problem of checking whether the feature works to the user. > > > > Hi, > > May be you are using hugetlbfs as memory backend? Not exactly hugepages, but I had: which resulted into the following commandline to instantiate memory: -object memory-backend-file,id=pc.ram,mem-path=/var/lib/libvirt/qemu/ram/6-upstream-bj/pc.ram,share=yes,size=33554432000,host-nodes=0,policy=bind \ When I've removed it I got: -object memory-backend-ram,id=pc.ram,size=33554432000,host-nodes=0,policy=bind \ And the migration didn't fail in my quick test. I'll have a more detailed look later, thanks for the pointer. > I totally agree that we need somehow check that kernel and VM memory backend > support the feature before one can enable the capability. > Need to think about that.. Definitely. Also note that memory backed by memory-backend-file will be more and more common, for cases such as virtiofs DAX sharing and similar.