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 9E66BC07545 for ; Wed, 25 Oct 2023 14:49:13 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qvfBB-00040E-Fg; Wed, 25 Oct 2023 10:48:17 -0400 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 1qvfB8-000401-Ha for qemu-devel@nongnu.org; Wed, 25 Oct 2023 10:48:14 -0400 Received: from smtp-out1.suse.de ([2001:67c:2178:6::1c]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qvfB6-0006WK-Uk for qemu-devel@nongnu.org; Wed, 25 Oct 2023 10:48:14 -0400 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 5A52121DDD; Wed, 25 Oct 2023 14:48:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1698245291; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=atDFOnLGSgZonzBNTuypCP3mR5NiBcjR4QghiPJgo0Y=; b=YFmGYSJMMeR4qxk6/ZFQxM94wtxIcHlA149EgiNyZg4LhfNn+KPSDxYj46ygIKR68nreKh VDSBRkEwMISulyzD2jQpoAN8FMpAgosd44Xe2aPv45ZI90iwckywOk9zR0ql8hL8+VqosS 9aRcs5pLlAjnwRj6G6tkFcBMNS5r7Po= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1698245291; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=atDFOnLGSgZonzBNTuypCP3mR5NiBcjR4QghiPJgo0Y=; b=T0MsNu3DJjjAdD83OpRDBk70XhfIEJ1k3SDiH/xj5K0PgaofFG5Un/ZLI7q//ZDSl91O3/ Bf2Q0qYu568G3jAg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id DFDBD138E9; Wed, 25 Oct 2023 14:48:10 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id NXl0KqoqOWWEJgAAMHmgww (envelope-from ); Wed, 25 Oct 2023 14:48:10 +0000 From: Fabiano Rosas To: =?utf-8?Q?Daniel_P=2E_Berrang=C3=A9?= Cc: qemu-devel@nongnu.org, armbru@redhat.com, Juan Quintela , Peter Xu , Leonardo Bras , Claudio Fontana , Eric Blake Subject: Re: [PATCH v2 28/29] migration: Add direct-io parameter In-Reply-To: References: <20231023203608.26370-1-farosas@suse.de> <20231023203608.26370-29-farosas@suse.de> Date: Wed, 25 Oct 2023 11:48:08 -0300 Message-ID: <87a5s6ep1z.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Authentication-Results: smtp-out1.suse.de; none X-Spamd-Result: default: False [-5.10 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; BAYES_HAM(-1.00)[87.21%]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-3.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-1.00)[-1.000]; RCPT_COUNT_SEVEN(0.00)[8]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[] Received-SPF: pass client-ip=2001:67c:2178:6::1c; envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 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, RCVD_IN_DNSWL_MED=-2.3, 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: 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 Daniel P. Berrang=C3=A9 writes: > On Mon, Oct 23, 2023 at 05:36:07PM -0300, Fabiano Rosas wrote: >> Add the direct-io migration parameter that tells the migration code to >> use O_DIRECT when opening the migration stream file whenever possible. >>=20 >> This is currently only used for the secondary channels of fixed-ram >> migration, which can guarantee that writes are page aligned. > > When you say "secondary channels", I presume you're meaning that > the bulk memory regions will be written with O_DIRECT, while > general vmstate will use normal I/O on the main channel ? If so, > could we explain that a little more directly. Yes, the main channel writes via QEMUFile, so no O_DIRECT. The channels created via multifd_new_send_channel_create() have O_DIRECT enabled. > Having a mixture of O_DIRECT and non-O_DIRECT I/O on the same > file is a little bit of an unusual situation. It will work for > us because we're writing to different regions of the file in > each case. > > Still I wonder if it would be sane in the outgoing case to > include a fsync() on the file in the main channel, to guarantee > that the whole saved file is on-media at completion ? Or perhaps > suggest in QAPI that mgmts might consider doing a fsync > themselves ? I think that should be present in QIOChannelFile in general. Not even related to this series. I'll add it at qio_channel_file_close() unless you object.