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 Received: from lists.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3D64EF364BE for ; Thu, 9 Apr 2026 21:49:51 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wAxFL-0003GU-4s; Thu, 09 Apr 2026 17:49:07 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wAxFJ-0003GE-DA for qemu-devel@nongnu.org; Thu, 09 Apr 2026 17:49:05 -0400 Received: from mx.treblig.org ([2a00:1098:5b::1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wAxFG-0001ZF-Ve for qemu-devel@nongnu.org; Thu, 09 Apr 2026 17:49:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=treblig.org ; s=bytemarkmx; h=Content-Type:MIME-Version:Message-ID:Subject:From:Date:From :Subject; bh=I3+zygPDdrYt1oWBgZV98MSYzKehFQGf3kqAyk4J2Kw=; b=IKPOm9jvQ4NvrCkt 0aFMPpQbnaDJ/IgKjwY2/w3+y7zBmG/lMokwer3Zh50rD5ZuKxr3lXHljyqTE4ytWevDFjvk1kdBt BOGqyK9Hdhldc9OIciU8Khty6iuAjq34bsHX35279EyJ1iTt+DgXhk0nuoNTaW3Zjo4OuZQg80pQr 3z/OrGX6QCYKF7DnE/jz1FAd7x4DXfUlxZ4hW/zq001/POY33rloygk6VeBntgugVDMVhfA/l1OOi hvGhbGvlldup57SRSjDSA3+e3q5kecV2F+AQmTLXJVr4Lf2Bm8c0BrpYyBu3oOwgOPAAL+IoRKGFp gQoy1L0IJzuwefd5HQ==; Received: from dg by mx.treblig.org with local (Exim 4.98.2) (envelope-from ) id 1wAxFB-00000007HfO-3lz4; Thu, 09 Apr 2026 21:48:57 +0000 Date: Thu, 9 Apr 2026 21:48:57 +0000 From: "Dr. David Alan Gilbert" To: Peter Xu Cc: qemu-devel@nongnu.org, "Maciej S . Szmigiero" , Daniel P =?iso-8859-1?Q?=2E_Berrang=E9?= , Zhiyi Guo , Juraj Marcin , Prasad Pandit , Avihai Horon , Kirti Wankhede , =?iso-8859-1?Q?C=E9dric?= Le Goater , Fabiano Rosas , Joao Martins , Markus Armbruster , Alex Williamson Subject: Re: [PATCH 13/14] migration/qapi: Introduce system-wise "remaining" reports Message-ID: References: <20260408165559.157108-1-peterx@redhat.com> <20260408165559.157108-14-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20260408165559.157108-14-peterx@redhat.com> X-Chocolate: 70 percent or better cocoa solids preferably X-Operating-System: Linux/6.12.74+deb13+1-amd64 (x86_64) X-Uptime: 21:48:18 up 27 days, 23:01, 2 users, load average: 0.02, 0.03, 0.00 User-Agent: Mutt/2.2.13 (2024-03-09) Received-SPF: pass client-ip=2a00:1098:5b::1; envelope-from=dg@treblig.org; helo=mx.treblig.org 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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org * Peter Xu (peterx@redhat.com) wrote: > Currently, mgmt can only query for remaining RAM, not system-wise remaining > data. It was not a problem before, because for a very long time RAM was > the only part that matters. > > After VFIO migrations landed upstream, it may not be true anymore > especially considering that there can be GPU devices that contain GBs of > device states. > > Add a new "remaining" field in query-migrate results, reflecting > system-wise remaining data, which will include everything (e.g. VFIO). Of course you realise the next thing people will ask for is being able to ask *which* vfio device is the one that's busy. Reviewed-by: Dr. David Alan Gilbert > This information will be useful for mgmt to implement generic way of stall > detection that covers all system resources. Say, when system remaining > data does not decrease anymore for a relatively long period of time, then > it may mean that there is a challenge of converging, so mgmt can act based > on how this value changes over time (especially if sampled after each > migration iteration). > > Before this patch, "expected_downtime" almost played this role. For > example, by monitoring "expected_downtime" at the beginning of each > iteration can in most cases also reflect the progress of migration > system-wise. Said that, "expected_downtime" was always calculated based on > a bandwidth value that can fluctuate a lot if avail-switchover-bandwidth is > not used. This new "remaining" field will remove that part of uncertainty > for mgmt. > > With the new field, HMP "info migrate" now reports this: > > (qemu) info migrate > Status: active > Time (ms): total=12080, setup=14, exp_down=300 > Remaining (bytes): 1.36 GiB <------------------- newline > RAM info: > Throughput (Mbps): 840.50 > Sizes: pagesize=4 KiB, total=4.02 GiB > Transfers: transferred=1.18 GiB, remain=1.36 GiB > Channels: precopy=1.18 GiB, multifd=0 B, postcopy=0 B > Page Types: normal=307923, zero=388148 > Page Rates (pps): transfer=25660 > Others: dirty_syncs=1 > > It should be the same value as RAM's remaining report when VFIO is not > involved, and it should report more than that when VFIO is involved. > > Cc: Markus Armbruster > Cc: Dr. David Alan Gilbert > Signed-off-by: Peter Xu > --- > qapi/migration.json | 4 ++++ > migration/migration-hmp-cmds.c | 5 +++++ > migration/migration.c | 11 +++++++++++ > 3 files changed, 20 insertions(+) > > diff --git a/qapi/migration.json b/qapi/migration.json > index e3ad3f0604..a6e24b5685 100644 > --- a/qapi/migration.json > +++ b/qapi/migration.json > @@ -300,6 +300,9 @@ > # average memory load of the virtual CPU indirectly. Note that > # zero means guest doesn't dirty memory. (Since 8.1) > # > +# @remaining: amount of bytes remaining to be migrated system-wise, > +# includes both RAM and all devices (like VFIO). (Since 11.1) > +# > # Features: > # > # @unstable: Members @postcopy-latency, @postcopy-vcpu-latency, > @@ -310,6 +313,7 @@ > ## > { 'struct': 'MigrationInfo', > 'data': {'*status': 'MigrationStatus', '*ram': 'MigrationRAMStats', > + '*remaining': 'uint64', > '*vfio': 'VfioStats', > '*xbzrle-cache': 'XBZRLECacheStats', > '*total-time': 'int', > diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c > index 0a193b8f54..721c211086 100644 > --- a/migration/migration-hmp-cmds.c > +++ b/migration/migration-hmp-cmds.c > @@ -178,6 +178,11 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict) > } > } > > + if (info->has_remaining) { > + g_autofree char *remaining = size_to_str(info->remaining); > + monitor_printf(mon, "Remaining (bytes): \t%s\n", remaining); > + } > + > if (info->has_socket_address) { > SocketAddressList *addr; > > diff --git a/migration/migration.c b/migration/migration.c > index 4010e5dcf5..c2aa145106 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -1076,6 +1076,16 @@ static void populate_time_info(MigrationInfo *info, MigrationState *s) > } > } > > +static void populate_global_info(MigrationInfo *info, MigrationState *s) > +{ > + MigPendingData data = { }; > + > + qemu_savevm_query_pending(&data, false); > + > + info->has_remaining = true; > + info->remaining = data.total_bytes; > +} > + > static void populate_ram_info(MigrationInfo *info, MigrationState *s) > { > size_t page_size = qemu_target_page_size(); > @@ -1177,6 +1187,7 @@ static void fill_source_migration_info(MigrationInfo *info) > /* TODO add some postcopy stats */ > populate_time_info(info, s); > populate_ram_info(info, s); > + populate_global_info(info, s); > migration_populate_vfio_info(info); > break; > case MIGRATION_STATUS_COLO: > -- > 2.53.0 > -- -----Open up your eyes, open up your mind, open up your code ------- / Dr. David Alan Gilbert | Running GNU/Linux | Happy \ \ dave @ treblig.org | | In Hex / \ _________________________|_____ http://www.treblig.org |_______/