From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <f.ebner@proxmox.com> Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id 7B331715BE for <pve-devel@lists.proxmox.com>; Thu, 8 Apr 2021 12:33:22 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 36B7519F6F for <pve-devel@lists.proxmox.com>; Thu, 8 Apr 2021 12:33:22 +0200 (CEST) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [212.186.127.180]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id 8CA8A19F40 for <pve-devel@lists.proxmox.com>; Thu, 8 Apr 2021 12:33:20 +0200 (CEST) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 5394B45A0B for <pve-devel@lists.proxmox.com>; Thu, 8 Apr 2021 12:33:20 +0200 (CEST) From: Fabian Ebner <f.ebner@proxmox.com> To: pve-devel@lists.proxmox.com Date: Thu, 8 Apr 2021 12:33:10 +0200 Message-Id: <20210408103316.7619-1-f.ebner@proxmox.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.007 Adjusted score from AWL reputation of From: address KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment RCVD_IN_DNSWL_MED -2.3 Sender listed at https://www.dnswl.org/, medium trust SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record URIBL_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [qemuserver.pm, qemuconfig.pm, qemu.pm] Subject: [pve-devel] [POC qemu-server] fix 3303: allow "live" upgrade of qemu version X-BeenThere: pve-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox VE development discussion <pve-devel.lists.proxmox.com> List-Unsubscribe: <https://lists.proxmox.com/cgi-bin/mailman/options/pve-devel>, <mailto:pve-devel-request@lists.proxmox.com?subject=unsubscribe> List-Archive: <http://lists.proxmox.com/pipermail/pve-devel/> List-Post: <mailto:pve-devel@lists.proxmox.com> List-Help: <mailto:pve-devel-request@lists.proxmox.com?subject=help> List-Subscribe: <https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel>, <mailto:pve-devel-request@lists.proxmox.com?subject=subscribe> X-List-Received-Date: Thu, 08 Apr 2021 10:33:22 -0000 The code is in a very early state, I'm just sending this to discuss the idea. I didn't do a whole lot of testing yet, but it does seem to work. The idea is rather simple: 1. save the state to ramfs 2. stop the VM 3. start the VM loading the state This approach solves the problem that our stack is (currently) not designed to have multiple instances with the same VM ID running. To do so, we'd need to handle config locking, sockets, pid file, passthrough resources?, etc. Another nice feature of this approach is that it doesn't require touching the vm_start or migration code at all, avoiding further bloating. Thanks to Fabian G. and Stefan for inspiring this idea: Fabian G. suggested using the suspend to disk + start route if the required changes to our stack would turn out to be infeasable. Stefan suggested migrating to a dummy VM (outside our stack) which just holds the state and migrating back right away. It seems that dummy VM is in fact not even needed ;) If we really really care about smallest possible downtime, this approach might still be the best, and we'd need to start the dummy VM while the backwards migration runs (resulting in two times the migration downtime). But it does have more moving parts and requires some migration/startup changes. Fabian Ebner (6): create vmstate_size helper create savevm_monitor helper draft of upgrade_qemu function draft of qemuupgrade API call add timing for testing add usleep parameter to savevm_monitor PVE/API2/Qemu.pm | 60 ++++++++++++++++++++++ PVE/QemuConfig.pm | 10 +--- PVE/QemuServer.pm | 125 +++++++++++++++++++++++++++++++++++++++------- 3 files changed, 170 insertions(+), 25 deletions(-) -- 2.20.1