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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 0751BC43613 for ; Mon, 24 Jun 2019 10:51:45 +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 D6E2F20674 for ; Mon, 24 Jun 2019 10:51:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D6E2F20674 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]:49706 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hfMZa-00053z-It for qemu-devel@archiver.kernel.org; Mon, 24 Jun 2019 06:51:43 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49186) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hfMZ4-0004fO-5U for qemu-devel@nongnu.org; Mon, 24 Jun 2019 06:51:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hfMZ2-0000PY-RD for qemu-devel@nongnu.org; Mon, 24 Jun 2019 06:51:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37554) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hfMZ2-0000O1-LG for qemu-devel@nongnu.org; Mon, 24 Jun 2019 06:51:08 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5E4B2368FF for ; Mon, 24 Jun 2019 10:51:06 +0000 (UTC) Received: from localhost (unknown [10.43.2.182]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3E67C1001B01; Mon, 24 Jun 2019 10:51:02 +0000 (UTC) Date: Mon, 24 Jun 2019 12:50:57 +0200 From: Igor Mammedov To: "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" Message-ID: <20190624125057.312554c2@redhat.com> In-Reply-To: <20190624093655.GE17698@redhat.com> References: <20190620114116.27254-1-imammedo@redhat.com> <87blynv1lu.fsf@dusky.pond.sub.org> <20190624093655.GE17698@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Mon, 24 Jun 2019 10:51:06 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [libvirt] [PATCH] deprecate -mem-path fallback to anonymous RAM 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: libvir-list@redhat.com, Markus Armbruster , ehabkost@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, 24 Jun 2019 10:36:55 +0100 Daniel P. Berrang=C3=A9 wrote: > On Mon, Jun 24, 2019 at 10:17:33AM +0200, Markus Armbruster wrote: > > Igor Mammedov writes: > > =20 > > > Fallback might affect guest or worse whole host performance > > > or functionality if backing file were used to share guest RAM > > > with another process. > > > > > > Patch deprecates fallback so that we could remove it in future > > > and ensure that QEMU will provide expected behavior and fail if > > > it can't use user provided backing file. > > > > > > Signed-off-by: Igor Mammedov > > > --- > > > PS: > > > Patch is written on top of > > > [PATCH v4 0/3] numa: deprecate '-numa node, mem' and default memor= y distribution > > > to avoid conflicts in qemu-deprecated.texi > > > > > > numa.c | 4 ++-- > > > qemu-deprecated.texi | 8 ++++++++ > > > 2 files changed, 10 insertions(+), 2 deletions(-) > > > > > > diff --git a/numa.c b/numa.c > > > index 91a29138a2..53d67b8ad9 100644 > > > --- a/numa.c > > > +++ b/numa.c > > > @@ -494,8 +494,8 @@ static void allocate_system_memory_nonnuma(Memory= Region *mr, Object *owner, > > > if (mem_prealloc) { > > > exit(1); > > > } > > > - error_report("falling back to regular RAM allocation."); > > > - > > > + warn_report("falling back to regular RAM allocation. " > > > + "Fallback to RAM allocation is deprecated.")= ; =20 > >=20 > > Can we give the user clues on how to avoid the deprecated fallback? =20 >=20 > There's nothing a user can do aside from ensuring they have sufficient > free memory before launching QEMU to satisfy the huge pag request. >=20 > Probably just needs changing to do. >=20 > "This is deprecated, future QEMU releases will exit when > huge pages cannot be allocated" Also it could be that users might use other than hugepages backing storage, that's why I completely left concrete advice out from suggestion. User should know what he/she is doing when providing mem-path, if user supplies mis-configured path QEMU will print error from memory-backend-file if/when allocation fails. > Regards, > Daniel