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 EC6EEC46467 for ; Wed, 11 Jan 2023 04:35:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pFSpL-0005Db-8p; Tue, 10 Jan 2023 23:35:03 -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 1pFSpI-0005D0-PI for qemu-devel@nongnu.org; Tue, 10 Jan 2023 23:35:00 -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 1pFSpH-0000Ze-A0 for qemu-devel@nongnu.org; Tue, 10 Jan 2023 23:35:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1673411698; h=from:from:reply-to:subject:subject: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=zgD4PXusvR/f8onznAaCZ7PK5c1IpTpp3SjUj44+/hM=; b=PqmACmlYf1o4jFyAarYlxOctyvWTBQegtSaV/id3lyK4DLoHA76M78dn7bpGpTC9p6+dov MnanTbfR0GLRkQxHLj1pA2t97jjhHmTqs9dPUJ30GQgx/Spyig9+iUmN8yU2zbhzKCHYOY H/S3L+NPB2WYGZ6kL/pRzAXNsm+W9fk= Received: from mail-oa1-f72.google.com (mail-oa1-f72.google.com [209.85.160.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-64-vWvESvaXNAyOSEOOc7xtfg-1; Tue, 10 Jan 2023 23:34:56 -0500 X-MC-Unique: vWvESvaXNAyOSEOOc7xtfg-1 Received: by mail-oa1-f72.google.com with SMTP id 586e51a60fabf-150bde26feeso4467688fac.4 for ; Tue, 10 Jan 2023 20:34:56 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=zgD4PXusvR/f8onznAaCZ7PK5c1IpTpp3SjUj44+/hM=; b=rnciakVWxCZhSonnWN9wIOjeOb/NRUvrXZqYHo3L0sD99vs41273DSO4P50FwlW/Kc G+Wxbs4kPEuXwRFu/ro3dy8w34o6w3eM5GAwi5O1LqTuWrwAA6YrIN0gvP7fLM/Bds9b zW8kVklf78KNrvoWg35bRUKoE8U6GVJVgHKx9+bP0XNDPq0mLDhCcB/48pZPRVOtOBPh Ushszw4M7PtVI+zbjBuc0xfPvlaCnxTxmUqjEczrHHutOSNS/NLPlbKwbYhGm40IUr2h q1HCTshN80t5WdE8EWAg8tmGIyFCW4Zljd9agrbwJyzVXUoLg8nEm11v/rGWoDNCwV9Z NQ4g== X-Gm-Message-State: AFqh2kp0B4GXdnsGRXOqLJXdD1c1qQBZrRXA2TwWR/fOgPdcOz5CE9o1 88b961kreKDkOa4Hd0i43qDhXYmbCc0TrgnXpQ8GuEHvKc/3SzvwnsQeLIYM5V+CpQq4rgv3o54 1talr7X+ftjfF51UpI0HBQOPRmVoE7SI= X-Received: by 2002:a05:6870:4413:b0:144:a97b:1ae2 with SMTP id u19-20020a056870441300b00144a97b1ae2mr3875206oah.35.1673411696145; Tue, 10 Jan 2023 20:34:56 -0800 (PST) X-Google-Smtp-Source: AMrXdXuyMqZcjHw/M06BFHqNcQ8h54g0nyWyx+EKsueHbx8EXtdJWkU/SxGfIzlt/iuEEhLTIKCkC9JEE/Ys2460VMs= X-Received: by 2002:a05:6870:4413:b0:144:a97b:1ae2 with SMTP id u19-20020a056870441300b00144a97b1ae2mr3875192oah.35.1673411695937; Tue, 10 Jan 2023 20:34:55 -0800 (PST) MIME-Version: 1.0 References: <20221205170436.2977336-1-eperezma@redhat.com> <20221205170436.2977336-11-eperezma@redhat.com> In-Reply-To: From: Jason Wang Date: Wed, 11 Jan 2023 12:34:44 +0800 Message-ID: Subject: Re: [RFC PATCH for 8.0 10/13] virtio-net: Migrate vhost inflight descriptors To: Parav Pandit Cc: =?UTF-8?Q?Eugenio_P=C3=A9rez?= , "qemu-devel@nongnu.org" , Liuxiangdong , Stefan Hajnoczi , Harpreet Singh Anand , Gautam Dawar , Zhu Lingshan , Cindy Lu , Si-Wei Liu , "Michael S. Tsirkin" , "Dr. David Alan Gilbert" , Laurent Vivier , Eli Cohen , Stefano Garzarella , Juan Quintela Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=jasowang@redhat.com; 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, 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_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 Tue, Jan 10, 2023 at 11:02 AM Parav Pandit wrote: > > Hi Jason, > > > From: Jason Wang > > Sent: Monday, December 5, 2022 10:25 PM > > > > > A dumb question, any reason we need bother with virtio-net? It looks to= me it's > > not a must and would complicate migration compatibility. > > Virtio net vdpa device is processing the descriptors out of order. > This vdpa device doesn=E2=80=99t offer IN_ORDER flag. > > And when a VQ is suspended it cannot complete these descriptors as some d= ummy zero length completions. > The guest VM is flooded with [1]. Yes, but any reason for the device to do out-of-order for RX? > > So it is needed for the devices that doesn=E2=80=99t offer IN_ORDER featu= re. > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tr= ee/drivers/net/virtio_net.c?h=3Dv6.2-rc3#n1252 It is only enabled in a debug kernel which should be harmless? Thanks >