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 ws5-mx01.kavi.com (ws5-mx01.kavi.com [34.193.7.191]) (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 B3528EC8759 for ; Thu, 7 Sep 2023 19:55:55 +0000 (UTC) Received: from lists.oasis-open.org (oasis.ws5.connectedcommunity.org [10.110.1.242]) by ws5-mx01.kavi.com (Postfix) with ESMTP id 5031161275 for ; Thu, 7 Sep 2023 19:55:53 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id F30B698660E for ; Thu, 7 Sep 2023 19:55:52 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by lists.oasis-open.org (Postfix) with QMQP id D95AB986602; Thu, 7 Sep 2023 19:55:52 +0000 (UTC) Mailing-List: contact virtio-dev-help@lists.oasis-open.org; run by ezmlm List-ID: Sender: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id B99BB9866B2 for ; Thu, 7 Sep 2023 19:55:52 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: Y7PXcdM_OlaP3Zeoi4f6nw-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694116549; x=1694721349; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=AZ9ZRaGY7HhpgVeNCCze9OatONauXr+5NAfTMIMyxfY=; b=kzvMe6j3JJ9sy9V7xKpH1WAPbBfxn1nOHq4ADxtoscjUXNSY5/S8b5HR4hwg71QYAi nRi2EAS1uGjGn/ZdiPFWUrYId6W2D0GfYRopGEpoprIMdTOJRY6QpG0tebWyTzOgWyyZ Y10Ea5OkGf2X9eVeVChxOO/e8bZRm8uraemfyiF0Ov7Uu0hwLqsQSUqK6WWqNtY8/6XW FqL+8ArugSbm5IN8pQW1qTV7ncH74q6I/KvFbXJ+JegHJN+kOArEDXFVPmmhcVtgDa9P 7xPPP3qE87I/4sX9l6OfN2JS9+gxatghMCMSSrfjOxQKWAKM96Yv46OKIQOIjtDxM4IH 14fg== X-Gm-Message-State: AOJu0YzCapM+n6KCJvSL5hzejp1J6F8J+xGQqChN9IVprZhYwMolD95S E1rS3QGeL9buMq0Iuc3nUadwxJJzh+SMBiYW3JVWF1+nJvwNo4S1DeOLFTMKmN22jhRXy+uP4mK FaZU64TNtJtaoQWIjcvdv62F9Ax2vdbOdTDBT X-Received: by 2002:a17:906:3042:b0:9a1:d2ef:3e3c with SMTP id d2-20020a170906304200b009a1d2ef3e3cmr226656ejd.44.1694116549013; Thu, 07 Sep 2023 12:55:49 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHRLN7FZqhdys/YrgfIoahZwgyaXbFDSpBzBjdV5ydVjvTBGYb49w4TdI4srloesuwE0GCxzA== X-Received: by 2002:a17:906:3042:b0:9a1:d2ef:3e3c with SMTP id d2-20020a170906304200b009a1d2ef3e3cmr226648ejd.44.1694116548652; Thu, 07 Sep 2023 12:55:48 -0700 (PDT) Date: Thu, 7 Sep 2023 15:55:44 -0400 From: "Michael S. Tsirkin" To: Eugenio Perez Martin Cc: "Zhu, Lingshan" , jasowang@redhat.com, cohuck@redhat.com, stefanha@redhat.com, virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org Message-ID: <20230907155414-mutt-send-email-mst@kernel.org> References: <20230906081637.32185-1-lingshan.zhu@intel.com> <20230906042851-mutt-send-email-mst@kernel.org> <20230906094742-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Subject: [virtio-dev] Re: [virtio-comment] [PATCH 0/5] virtio: introduce SUSPEND bit and vq state On Thu, Sep 07, 2023 at 12:57:58PM +0200, Eugenio Perez Martin wrote: > On Wed, Sep 6, 2023 at 3:49 PM Michael S. Tsirkin wrote: > > > > On Wed, Sep 06, 2023 at 04:38:44PM +0800, Zhu, Lingshan wrote: > > > > > > > > > On 9/6/2023 4:29 PM, Michael S. Tsirkin wrote: > > > > On Wed, Sep 06, 2023 at 04:16:32PM +0800, Zhu Lingshan wrote: > > > > > This series introduces > > > > > 1)a new SUSPEND bit in the device status > > > > > Which is used to suspend the device, so that the device states > > > > > and virtqueue states are stabilized. > > > > > > > > > > 2)virtqueue state and its accessor, to get and set last_avail_idx > > > > > and last_used_idx of virtqueues. > > > > > > > > > > The main usecase of these new facilities is Live Migration. > > > > > > > > > > Future work: dirty page tracking and in-flight descriptors. > > > > oh that answers my question - it's not covered. > > > > I don't think we can merge this without in-flight descriptor > > > > support. > > > When SUSPEND, we require the device wait until all descriptors that > > > being processed to finish and mark them as used.(In patch 2) > > > at this point there may be no in-flight descriptors, so this is still > > > self-consistent. The tracker for in-flight descriptors is excluded to > > > make this series small and focus. > > > > Does not work generally. > > Imagine RX ring of a network device for example. You can wait > > as long as you can but if there's no incoming network traffic > > buffers will not be used. > > > > The patch should word it differently, yes. > > QEMU's vhost-kernel net handler currently assumes the device will use > the descriptors sequentially from avail_idx. In that case, it is > possible to simply finish receiving in-flight packets (not buffers) > and just stop receiving new packets. As all packets has been received, > we have a valid used-idx, and the device at resume (or the destination > device at migration) can just fetch all buffers from there. > > I may have a better wording of this in other mails. > > Would it work to use this solution with in_order, and defer the > inflight buffers handling for the future? It would allow to keep this > series small. > > Thanks! in_order isn't used widely so I doubt depending on it is wise. And again the whole things has to be rewritten with admin queue and the group owner generally does not know whether in_order was negotiated by member or not. > > Also please, keep to the spec terminology. buffers are used not > > descriptors. Best to keep it straight errors will not leak into > > spec. > > > > > > > > > > > > > > > > > > > > > This series addresses many comments from Jason, Stefan and Eugenio > > > > > from RFC series. > > > > > > > > > > Zhu Lingshan (5): > > > > > virtio: introduce vq state as basic facility > > > > > virtio: introduce SUSPEND bit in device status > > > > > virtqueue: constraints for virtqueue state > > > > > virtqueue: ignore resetting vqs when SUSPEND > > > > > virtio-pci: implement VIRTIO_F_QUEUE_STATE > > > > > > > > > > content.tex | 118 ++++++++++++++++++++++++++++++++++++++++++++++ > > > > > transport-pci.tex | 18 +++++++ > > > > > 2 files changed, 136 insertions(+) > > > > > > > > > > -- > > > > > 2.35.3 > > > > > > > > > > > > > > > This publicly archived list offers a means to provide input to the > > > > > OASIS Virtual I/O Device (VIRTIO) TC. > > > > > > > > > > In order to verify user consent to the Feedback License terms and > > > > > to minimize spam in the list archive, subscription is required > > > > > before posting. > > > > > > > > > > Subscribe: virtio-comment-subscribe@lists.oasis-open.org > > > > > Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org > > > > > List help: virtio-comment-help@lists.oasis-open.org > > > > > List archive: https://lists.oasis-open.org/archives/virtio-comment/ > > > > > Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf > > > > > List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists > > > > > Committee: https://www.oasis-open.org/committees/virtio/ > > > > > Join OASIS: https://www.oasis-open.org/join/ > > > > > > > --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org