From: Parav Pandit <parav@nvidia.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: "virtio-comment@lists.oasis-open.org"
<virtio-comment@lists.oasis-open.org>,
"hengqi@linux.alibaba.com" <hengqi@linux.alibaba.com>,
"david.edmondson@oracle.com" <david.edmondson@oracle.com>,
"xuanzhuo@linux.alibaba.com" <xuanzhuo@linux.alibaba.com>,
"sburla@marvell.com" <sburla@marvell.com>,
Shahaf Shuler <shahafs@nvidia.com>,
"virtio@lists.oasis-open.org" <virtio@lists.oasis-open.org>
Subject: [virtio-comment] RE: [virtio] [PATCH requirements v5 3/7] net-features: Add low latency receive queue requirements
Date: Mon, 11 Sep 2023 16:03:10 +0000 [thread overview]
Message-ID: <PH0PR12MB5481F9484EC98BB1A6CD6E68DCF2A@PH0PR12MB5481.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20230911134715.GC3803963@fedora>
> From: Stefan Hajnoczi <stefanha@redhat.com>
> Sent: Monday, September 11, 2023 7:17 PM
>
> If I understand correctly there is no longer a 1:1 correspondence between
> driver-supplied rx pages (available buffers) and received packets (used buffers).
> Instead, the device consumes portions of driver-supplied rx pages as needed
> and notifies the driver, and the entire rx page is marked used later when it has
> been fully consumed.
>
> The virtqueue model is based on submitting available buffers and completing
> used buffers, not individual DMA transfers. It's not possible to do DMA
> piecewise in this model. If you think about a VIRTIO over TCP transport that
> uses message-passing for available and used buffers, then it's clear the rx page
> approach breaks the model because only entire virtqueues buffers can be
> marked used (there is a 1:1 correspondence between available buffers and used
> buffers).
>
> Two options:
> 1. Extend the virtqueue model to support this.
> 2. Document this violation of the virtqueue model clearly but treat it
> as an exception that may lead to complications in the future (e.g.
> incompatibility with VIRTIO over TCP).
>
I don't think it a violation. It is an extension of a new model. PCI and MMIO will support it.
TCP transport may not be able support everything that exists today in PCI.
But I am not fully sure at present this as limitation.
I will consider #1 later in this month further.
This week occupied with the LM and flow filters that we want to review on Wed meet.
> I think it's worth investigating #1 to see whether the virtqueue model can be
> extended cleanly.
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/
next prev parent reply other threads:[~2023-09-11 16:03 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-18 4:35 [virtio-comment] [PATCH requirements v5 0/7] virtio net requirements for 1.4 Parav Pandit
2023-08-18 4:35 ` [virtio-comment] [PATCH requirements v5 1/7] net-features: Add requirements document for release 1.4 Parav Pandit
2023-08-21 10:44 ` David Edmondson
2023-08-18 4:35 ` [virtio-comment] [PATCH requirements v5 2/7] net-features: Add low latency transmit queue requirements Parav Pandit
2023-08-18 4:35 ` [virtio-comment] [PATCH requirements v5 3/7] net-features: Add low latency receive " Parav Pandit
2023-08-21 10:47 ` [virtio-comment] " David Edmondson
2023-08-22 6:12 ` [virtio-comment] " Parav Pandit
2023-09-11 13:47 ` [virtio-comment] Re: [virtio] " Stefan Hajnoczi
2023-09-11 16:03 ` Parav Pandit [this message]
2023-08-18 4:35 ` [virtio-comment] [PATCH requirements v5 4/7] net-features: Add notification coalescing requirements Parav Pandit
2023-08-18 4:35 ` [virtio-comment] [PATCH requirements v5 5/7] net-features: Add n-tuple receive flow filters requirements Parav Pandit
2023-08-21 5:06 ` [virtio-comment] " Heng Qi
2023-08-21 5:14 ` [virtio-comment] " Parav Pandit
2023-08-22 7:41 ` Parav Pandit
2023-08-18 4:35 ` [virtio-comment] [PATCH requirements v5 6/7] net-features: Add packet timestamp requirements Parav Pandit
2023-08-18 4:35 ` [virtio-comment] [PATCH requirements v5 7/7] net-features: Add header data split requirements Parav Pandit
2023-08-21 10:45 ` [virtio-comment] " David Edmondson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=PH0PR12MB5481F9484EC98BB1A6CD6E68DCF2A@PH0PR12MB5481.namprd12.prod.outlook.com \
--to=parav@nvidia.com \
--cc=david.edmondson@oracle.com \
--cc=hengqi@linux.alibaba.com \
--cc=sburla@marvell.com \
--cc=shahafs@nvidia.com \
--cc=stefanha@redhat.com \
--cc=virtio-comment@lists.oasis-open.org \
--cc=virtio@lists.oasis-open.org \
--cc=xuanzhuo@linux.alibaba.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).