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 (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 smtp.lore.kernel.org (Postfix) with ESMTPS id 129E4C5475B for ; Mon, 4 Mar 2024 01:31:23 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rgx8Z-0004gi-8k; Sun, 03 Mar 2024 20:29:03 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rgx8G-0002sG-MN for qemu-devel@nongnu.org; Sun, 03 Mar 2024 20:28:46 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rgx8F-0002UT-58 for qemu-devel@nongnu.org; Sun, 03 Mar 2024 20:28:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1709515721; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KQjfAx5fwudle9JMFQ3un6R3jAgdZL0axGO7bP69yRk=; b=ciRgfk0zOa3qfWNIp3Gqm9jtWVmYGbwRaXZNqqtMBj7d9MyQffNqA09z0j95CNhkINGoO7 Y3hQ7LOiV+yiRPyDjwe+QNdJTW0MmqX4V67sjuif6UW6SswSu6Q+HC97TIcAzJMxUiuUrE WTimxzpmRboAfNwbxwnKcOrdSmKUoYA= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-474-zJ38GSrmNoemaGbvBocP4w-1; Sun, 03 Mar 2024 20:28:37 -0500 X-MC-Unique: zJ38GSrmNoemaGbvBocP4w-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 707B93C0DD05; Mon, 4 Mar 2024 01:28:37 +0000 (UTC) Received: from x1n.redhat.com (unknown [10.72.116.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id 10D7A40C6EBA; Mon, 4 Mar 2024 01:28:33 +0000 (UTC) From: peterx@redhat.com To: qemu-devel@nongnu.org, Peter Maydell Cc: peterx@redhat.com, =?UTF-8?q?Daniel=20P=20=2E=20Berrang=C3=A9?= , Prasad Pandit , Fabiano Rosas Subject: [PULL 27/27] migration/multifd: Document two places for mapped-ram Date: Mon, 4 Mar 2024 09:26:34 +0800 Message-ID: <20240304012634.95520-28-peterx@redhat.com> In-Reply-To: <20240304012634.95520-1-peterx@redhat.com> References: <20240304012634.95520-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.589, 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_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: 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 From: Peter Xu Add two documentations for mapped-ram migration on two spots that may not be extremely clear. Reviewed-by: Fabiano Rosas Link: https://lore.kernel.org/r/20240301091524.39900-1-peterx@redhat.com Cc: Prasad Pandit [peterx: fix two English errors per Prasad] Signed-off-by: Peter Xu --- migration/multifd.c | 12 ++++++++++++ migration/ram.c | 8 +++++++- 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/migration/multifd.c b/migration/multifd.c index b4e5a9dfcc..d4a44da559 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -709,6 +709,18 @@ static bool multifd_send_cleanup_channel(MultiFDSendParams *p, Error **errp) { if (p->c) { migration_ioc_unregister_yank(p->c); + /* + * An explicit close() on the channel here is normally not + * required, but can be helpful for "file:" iochannels, where it + * will include fdatasync() to make sure the data is flushed to the + * disk backend. + * + * The object_unref() cannot guarantee that because: (1) finalize() + * of the iochannel is only triggered on the last reference, and + * it's not guaranteed that we always hold the last refcount when + * reaching here, and, (2) even if finalize() is invoked, it only + * does a close(fd) without data flush. + */ qio_channel_close(p->c, &error_abort); object_unref(OBJECT(p->c)); p->c = NULL; diff --git a/migration/ram.c b/migration/ram.c index 1f1b5297cf..c79e3de521 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -4258,7 +4258,13 @@ static int ram_load_precopy(QEMUFile *f) switch (flags & ~RAM_SAVE_FLAG_CONTINUE) { case RAM_SAVE_FLAG_MEM_SIZE: ret = parse_ramblocks(f, addr); - + /* + * For mapped-ram migration (to a file) using multifd, we sync + * once and for all here to make sure all tasks we queued to + * multifd threads are completed, so that all the ramblocks + * (including all the guest memory pages within) are fully + * loaded after this sync returns. + */ if (migrate_mapped_ram()) { multifd_recv_sync_main(); } -- 2.44.0