[{"id":3680627,"web_url":"http://patchwork.ozlabs.org/comment/3680627/","msgid":"","list_archive_url":null,"date":"2026-04-22T13:18:26","subject":"Re: [PATCH v2 13/16] migration: Remember total dirty bytes in\n mig_stats","submitter":{"id":89058,"url":"http://patchwork.ozlabs.org/api/people/89058/","name":"Juraj Marcin","email":"jmarcin@redhat.com"},"content":"On 2026-04-21 16:21, Peter Xu wrote:\n> Introduce this new counter to remember the total dirty bytes for the whole\n> system. It will be used for query-migrate command to fetch system-wise\n> remaining data.\n> \n> A prior attempt was made to not use this counter but query directly from\n> all the modules in a QMP handler, but it exposed some complexity not only\n> on migration state machine race conditions (where the query may be invoked\n> anytime of the state machine), or on locking implications (where some of\n> the query hooks may take BQL, which is illegal at least in a QMP handler).\n> For more information, see:\n> \n> https://lore.kernel.org/r/aeZMtxqrKWAMKzdN@x1.local\n> \n> This oneliner will resolve everything, except that it is not as accurate.\n> The hope is it is a worthwhile trade-off solution, after knowing above\n> challenges.\n> \n> Now, there is one more reason we should make each invocation of\n> save_live_iterate() to be lightweight, because this counter will only get\n> updated once for each loop over all save_live_iterate() hooks when present.\n> But that's always the goal.\n> \n> Signed-off-by: Peter Xu \n> ---\n> migration/migration-stats.h | 7 +++++++\n> migration/savevm.c | 7 +++++++\n> 2 files changed, 14 insertions(+)\n\nReviewed-by: Juraj Marcin ","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=TSAI7HOD;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=google header.b=ZYEp+QGw;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; helo=lists1p.gnu.org;\n envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n receiver=patchwork.ozlabs.org)"],"Received":["from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g10DX5GdLz1y2d\n\tfor ; Wed, 22 Apr 2026 23:19:08 +1000 (AEST)","from localhost ([::1] helo=lists1p.gnu.org)\n\tby lists1p.gnu.org with esmtp (Exim 4.90_1)\n\t(envelope-from )\n\tid 1wFXTb-0004JL-KV; Wed, 22 Apr 2026 09:18:47 -0400","from eggs.gnu.org ([2001:470:142:3::10])\n by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1wFXTa-0004J1-Kn\n for qemu-devel@nongnu.org; Wed, 22 Apr 2026 09:18:46 -0400","from us-smtp-delivery-124.mimecast.com ([170.10.129.124])\n by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.90_1) (envelope-from )\n id 1wFXTZ-0005ub-1r\n for qemu-devel@nongnu.org; Wed, 22 Apr 2026 09:18:46 -0400","from mail-pg1-f198.google.com (mail-pg1-f198.google.com\n [209.85.215.198]) by relay.mimecast.com with ESMTP with STARTTLS\n (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id\n us-mta-635-AF10AIt-Nn64lDSHR-UmEQ-1; Wed, 22 Apr 2026 09:18:42 -0400","by mail-pg1-f198.google.com with SMTP id\n 41be03b00d2f7-c79907d4c57so1256719a12.0\n for ; Wed, 22 Apr 2026 06:18:41 -0700 (PDT)","from fedora (193-179-61-20.customers.tmcz.cz. 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Szmigiero\" ","Subject":"Re: [PATCH v2 13/16] migration: Remember total dirty bytes in\n mig_stats","Message-ID":"","References":"<20260421202110.306051-1-peterx@redhat.com>\n <20260421202110.306051-14-peterx@redhat.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<20260421202110.306051-14-peterx@redhat.com>","Received-SPF":"pass client-ip=170.10.129.124; envelope-from=jmarcin@redhat.com;\n 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,\n DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001,\n SPF_HELO_PASS=-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":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"}}]