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 31880C05027 for ; Mon, 23 Jan 2023 08:21:52 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pJs5B-0003S0-54; Mon, 23 Jan 2023 03:21:37 -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 1pJs59-0003Rf-05 for qemu-devel@nongnu.org; Mon, 23 Jan 2023 03:21:35 -0500 Received: from 3.mo548.mail-out.ovh.net ([188.165.32.156]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pJs56-0001sR-E3 for qemu-devel@nongnu.org; Mon, 23 Jan 2023 03:21:34 -0500 Received: from mxplan5.mail.ovh.net (unknown [10.108.16.68]) by mo548.mail-out.ovh.net (Postfix) with ESMTPS id 9C8862289A; Mon, 23 Jan 2023 08:21:21 +0000 (UTC) Received: from kaod.org (37.59.142.99) by DAG8EX2.mxp5.local (172.16.2.72) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.16; Mon, 23 Jan 2023 09:21:20 +0100 Authentication-Results: garm.ovh; auth=pass (GARM-99G003c236452c-ce6a-415c-b31e-4eb968f8763a, 50F971C67E06351E5895DAE5ED0110D8D9269BCE) smtp.auth=groug@kaod.org X-OVh-ClientIp: 78.197.208.248 Date: Mon, 23 Jan 2023 09:21:19 +0100 From: Greg Kurz To: CC: Stefan Hajnoczi , "Dr. David Alan Gilbert" , Maxime Coquelin , Laurent Vivier , "Michael S. Tsirkin" , Yajun Wu , Peter Maydell , Parav Pandit , Subject: Re: [PATCH 0/2] vhost-user: Remove the nested event loop to unbreak the DPDK use case Message-ID: <20230123092119.074e456b@bahia> In-Reply-To: <20230119172424.478268-1-groug@kaod.org> References: <20230119172424.478268-1-groug@kaod.org> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.35; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [37.59.142.99] X-ClientProxiedBy: DAG7EX1.mxp5.local (172.16.2.61) To DAG8EX2.mxp5.local (172.16.2.72) X-Ovh-Tracer-GUID: 16678e64-6888-4caa-84ef-e2033f55300c X-Ovh-Tracer-Id: 4864169075651353010 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedvhedruddujedguddukecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemucehtddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpeffhffvvefukfgjfhfogggtgfhisehtjeertdertddvnecuhfhrohhmpefirhgvghcumfhurhiiuceoghhrohhugheskhgrohgurdhorhhgqeenucggtffrrghtthgvrhhnpeffheefheevleetieetheffjeetgfdttedtlefgieelfffhgedvteekvddttdehleenucffohhmrghinhepkhgvrhhnvghlrdhorhhgpdhrvgguhhgrthdrtghomhenucfkphepuddvjedrtddrtddruddpfeejrdehledrudegvddrleelnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepuddvjedrtddrtddruddpmhgrihhlfhhrohhmpeeoghhrohhugheskhgrohgurdhorhhgqedpnhgspghrtghpthhtohepuddprhgtphhtthhopehqvghmuhdquggvvhgvlhesnhhonhhgnhhurdhorhhgpdhsthgvfhgrnhhhrgesrhgvughhrghtrdgtohhmpdgughhilhgsvghrthesrhgvughhrghtrdgtohhmpdhmrgigihhmvgdrtghoqhhuvghlihhnsehrvgguhhgrthdrtghomhdplhhvihhvihgvrhesrhgvughhrghtrdgtohhmpdhmshhtsehrvgguhhgrthdrtghomhdphigrjhhunhifsehnvhhiughirgdrtghomhdpphgvthgvrhdrmhgrhiguvghllh eslhhinhgrrhhordhorhhgpdhprghrrghvsehnvhhiughirgdrtghomhdpqhgvmhhuqdhsthgrsghlvgesnhhonhhgnhhurdhorhhgpdfovfetjfhoshhtpehmohehgeekpdhmohguvgepshhmthhpohhuth Received-SPF: pass client-ip=188.165.32.156; envelope-from=groug@kaod.org; helo=3.mo548.mail-out.ovh.net X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-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: 2.1.29 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 On Thu, 19 Jan 2023 18:24:22 +0100 Greg Kurz wrote: > The nested event loop was introduced in QEMU 6.0 to allow servicing > of requests coming from the slave channel while waiting for an ack > from the back-end on the master socket. It turns out this is fragile > and breaks if the servicing of the slave channel causes a new message > to be sent on the master socket. This is exactly what happens when > using DPDK as reported in [0]. > > The only identified user for the nested loop is DAX enablement that > isn't upstream yet. Just drop the code for now. Some more clever > solution should be designed when the need to service concurrent > requests from both channels arises again. > > Greg Kurz (2): > Revert "vhost-user: Monitor slave channel in vhost_user_read()" > Revert "vhost-user: Introduce nested event loop in vhost_user_read()" > > hw/virtio/vhost-user.c | 100 ++++------------------------------------- > 1 file changed, 8 insertions(+), 92 deletions(-) > Hi Michael, Can you please merge this series as you kindly proposed in [0] ? This will help to fix [1] which is currently blocking downstream testing. Cheers, -- Greg [0] https://lore.kernel.org/qemu-devel/20230118060102-mutt-send-email-mst@kernel.org/ [1] https://bugzilla.redhat.com/show_bug.cgi?id=2155173