From: Stephen Hemminger <stephen@networkplumber.org>
To: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
Cc: <dev@dpdk.org>, <rasland@nvidia.com>, <matan@nvidia.com>,
<suanmingm@nvidia.com>
Subject: Re: [PATCH 1/1] doc: virtual function MTU settings has no meaning
Date: Mon, 28 Oct 2024 08:51:51 -0700 [thread overview]
Message-ID: <20241028085151.2bc312da@hermes.local> (raw)
In-Reply-To: <20241028144509.1612033-1-viacheslavo@nvidia.com>
On Mon, 28 Oct 2024 16:45:09 +0200
Viacheslav Ovsiienko <viacheslavo@nvidia.com> wrote:
> There is the mlx5 NIC limitations - configuring MTU
> for PCI Virtual Function has no meaning. The actual maximal
> packet size in VF's receiving is limited by MTU configured
> on the related PCI Physical Function, the DPDK datapath
> running over VF should be prepared to handle packets
> of this maximal size.
>
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
> ---
> doc/guides/nics/mlx5.rst | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
> index 8d1a1311d4..c7dcb74da7 100644
> --- a/doc/guides/nics/mlx5.rst
> +++ b/doc/guides/nics/mlx5.rst
> @@ -191,6 +191,13 @@ Limitations
> - IPv4/TCP with CVLAN filtering
> - L4 steering rules for port RSS of UDP, TCP and IP
>
> +- PCI Virtual Function MTU:
> +
> + Configuring MTU for PCI Virtual Function has no meaning.
> + The actual maximal packet size in VF's receiving is limited by MTU configured
> + on the related PCI Physical Function, the DPDK datapath running over VF should be
> + prepared to handle packets of this maximal size.
> +
This is true of many drivers not just MLX5.
And it is generally true that Maximum Receive Unit (MRU) can
be larger than Maximum Transmit Unit (MTU).
I would rather see a more precise definition of MTU in DPDK show up
in ethdev documentation than sprinkling bits in each vendor driver.
next prev parent reply other threads:[~2024-10-28 15:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-28 14:45 Viacheslav Ovsiienko
2024-10-28 15:51 ` Stephen Hemminger [this message]
2024-10-28 17:05 ` Slava Ovsiienko
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=20241028085151.2bc312da@hermes.local \
--to=stephen@networkplumber.org \
--cc=dev@dpdk.org \
--cc=matan@nvidia.com \
--cc=rasland@nvidia.com \
--cc=suanmingm@nvidia.com \
--cc=viacheslavo@nvidia.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 NNTP newsgroup(s).