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=-10.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 7C598C63777 for ; Tue, 24 Nov 2020 16:56:30 +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 9929B206D8 for ; Tue, 24 Nov 2020 16:56:29 +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="cq1G76fZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9929B206D8 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]:59422 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1khbcC-0005dW-DS for qemu-devel@archiver.kernel.org; Tue, 24 Nov 2020 11:56:28 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:51402) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1khbOL-0002p5-Jd for qemu-devel@nongnu.org; Tue, 24 Nov 2020 11:42:09 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:27676) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1khbOJ-0004OL-IK for qemu-devel@nongnu.org; Tue, 24 Nov 2020 11:42:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606236126; 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=iPlNU5or96iGvFpOMNsqM5K2rpovCYabGRGU96T+E68=; b=cq1G76fZmdpGylMayUlqAXU1feBaMvUXv4PdJKGHD6vMfnujNG++qWKhqx7vkWJ2EdRJMl zA11v4VxIbGryYcBbgoKvkiTywbQMD1yHEEmx88Y/LHmBCronMGa0jyXPM+S/fNfaYxqbJ 0JcgHygTfiRZbETJGfLHJsWRBYzJQPQ= 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-305-BqKHkxQrONKyAXtgFB9X0g-1; Tue, 24 Nov 2020 11:42:04 -0500 X-MC-Unique: BqKHkxQrONKyAXtgFB9X0g-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 135511007461; Tue, 24 Nov 2020 16:42:03 +0000 (UTC) Received: from work-vm (ovpn-115-42.ams2.redhat.com [10.36.115.42]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CFDC860864; Tue, 24 Nov 2020 16:41:57 +0000 (UTC) Date: Tue, 24 Nov 2020 16:41:55 +0000 From: "Dr. David Alan Gilbert" To: Andrey Gruzdev Subject: Re: [PATCH v3 0/7] UFFD write-tracking migration/snapshots Message-ID: <20201124164155.GI3366@work-vm> References: <20201119125940.20017-1-andrey.gruzdev@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <20201119125940.20017-1-andrey.gruzdev@virtuozzo.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@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=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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: zhang.zhanghailiang@huawei.com, Juan Quintela , qemu-devel@nongnu.org, Peter Xu , Markus Armbruster , chen.zhang@intel.com, Paolo Bonzini , Den Lunev Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Andrey Gruzdev (andrey.gruzdev@virtuozzo.com) wrote: > Changes with v3: > * coding style fixes to pass checkpatch test > * qapi/migration.json: change 'track-writes-ram' capability > * supported version to 6.0 > * fixes to commit message format > cc'ing in COLO people, since they could use this as well. > This patch series is a kind of 'rethinking' of Denis Plotnikov's ideas he's > implemented in his series '[PATCH v0 0/4] migration: add background snapshot'. > > Currently the only way to make (external) live VM snapshot is using existing > dirty page logging migration mechanism. The main problem is that it tends to > produce a lot of page duplicates while running VM goes on updating already > saved pages. That leads to the fact that vmstate image size is commonly several > times bigger then non-zero part of virtual machine's RSS. Time required to > converge RAM migration and the size of snapshot image severely depend on the > guest memory write rate, sometimes resulting in unacceptably long snapshot > creation time and huge image size. > > This series propose a way to solve the aforementioned problems. This is done > by using different RAM migration mechanism based on UFFD write protection > management introduced in v5.7 kernel. The migration strategy is to 'freeze' > guest RAM content using write-protection and iteratively release protection > for memory ranges that have already been saved to the migration stream. > At the same time we read in pending UFFD write fault events and save those > pages out-of-order with higher priority. > > How to use: > 1. Enable write-tracking migration capability > virsh qemu-monitor-command --hmp migrate_set_capability. > track-writes-ram on > > 2. Start the external migration to a file > virsh qemu-monitor-command --hmp migrate exec:'cat > ./vm_state' > > 3. Wait for the migration finish and check that the migration has completed. > state. > > Andrey Gruzdev (7): > introduce 'track-writes-ram' migration capability > introduce UFFD-WP low-level interface helpers > support UFFD write fault processing in ram_save_iterate() > implementation of write-tracking migration thread > implementation of vm_start() BH > the rest of write tracking migration code > introduce simple linear scan rate limiting mechanism > > include/exec/memory.h | 7 + > migration/migration.c | 338 +++++++++++++++++++++++++++++++- > migration/migration.h | 4 + > migration/ram.c | 439 +++++++++++++++++++++++++++++++++++++++++- > migration/ram.h | 4 + > migration/savevm.c | 1 - > migration/savevm.h | 2 + > qapi/migration.json | 7 +- > 8 files changed, 790 insertions(+), 12 deletions(-) > > -- > 2.25.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK