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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 4FFC8C54FCF for ; Wed, 25 Mar 2020 15:41:50 +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 300462073E for ; Wed, 25 Mar 2020 15:41:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 300462073E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=proxmox.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38546 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jH8A9-0006rV-As for qemu-devel@archiver.kernel.org; Wed, 25 Mar 2020 11:41:49 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45482) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jH89I-0005cC-95 for qemu-devel@nongnu.org; Wed, 25 Mar 2020 11:40:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jH89G-0007DQ-5j for qemu-devel@nongnu.org; Wed, 25 Mar 2020 11:40:56 -0400 Received: from proxmox-new.maurer-it.com ([212.186.127.180]:43364) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jH89F-0007Ba-UU for qemu-devel@nongnu.org; Wed, 25 Mar 2020 11:40:54 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id E9A6542EAC; Wed, 25 Mar 2020 16:40:49 +0100 (CET) Date: Wed, 25 Mar 2020 16:40:48 +0100 (CET) From: Dietmar Maurer To: Sergio Lopez Message-ID: <1427176168.41.1585150848553@webmail.proxmox.com> In-Reply-To: <20200325123905.4mygg2ljie7prtbc@dritchie> References: <2007060575.48.1585048408879@webmail.proxmox.com> <1512602350.59.1585056617632@webmail.proxmox.com> <1806708761.60.1585056799652@webmail.proxmox.com> <32c10c76-1c9f-3a6a-4410-09eebad0f6f3@redhat.com> <20200325081312.7wtz6crlgotsw5ul@dritchie> <20200325114639.rxwhs7h4bkxhkgsu@dritchie> <523142611.32.1585139388758@webmail.proxmox.com> <20200325123905.4mygg2ljie7prtbc@dritchie> Subject: Re: backup transaction with io-thread core dumps MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Priority: 3 Importance: Normal X-Mailer: Open-Xchange Mailer v7.10.2-Rev22 X-Originating-Client: open-xchange-appsuite X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 212.186.127.180 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: , Reply-To: Dietmar Maurer Cc: kwolf@redhat.com, "jsnow@redhat.com" , "qemu-devel@nongnu.org" , Stefan Hajnoczi , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" > On March 25, 2020 1:39 PM Sergio Lopez wrote: > > > On Wed, Mar 25, 2020 at 01:29:48PM +0100, Dietmar Maurer wrote: > > > As expected, if both BDS are running on the same IOThread (and thus, > > > the same AioContext), the problem is not reproducible. > > > > > > In a general sense, we could say that completion modes other than > > > "individual" are not supported for a transaction that may access > > > different AioContexts. I don't see a safe an easy way to fix this. We > > > could opt for simply detect and forbid such completion modes when the > > > BDS's are assigned to different AioContexts. Perhaps Kevin (in CC) has > > > a better idea. > > > > So the solution is to disable backups when using io-threads? > > > > I meant forbidding transactions with completion-mode == grouped. It > would be still possible running transactions (and thus, backups) with > completion-mode == individual, which is the default. As mentioned earlier, even a totally simple/normal backup job fails when using io-threads and the VM is under load. It results in a total VM freeze!