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Message-ID: <ZmMsUYFvUOndiX8g@nanopsycho.orion>
Date: Fri, 7 Jun 2024 17:50:41 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: Jason Gunthorpe <jgg@...dia.com>
Cc: David Ahern <dsahern@...nel.org>, Jakub Kicinski <kuba@...nel.org>,
Dan Williams <dan.j.williams@...el.com>,
Jonathan Corbet <corbet@....net>, Itay Avraham <itayavr@...dia.com>,
Leon Romanovsky <leon@...nel.org>, linux-doc@...r.kernel.org,
linux-rdma@...r.kernel.org, netdev@...r.kernel.org,
Paolo Abeni <pabeni@...hat.com>, Saeed Mahameed <saeedm@...dia.com>,
Tariq Toukan <tariqt@...dia.com>,
Andy Gospodarek <andrew.gospodarek@...adcom.com>,
Aron Silverton <aron.silverton@...cle.com>,
Christoph Hellwig <hch@...radead.org>, Jiri Pirko <jiri@...dia.com>,
Leonid Bloch <lbloch@...dia.com>,
Leon Romanovsky <leonro@...dia.com>, linux-cxl@...r.kernel.org,
patches@...ts.linux.dev
Subject: Re: [PATCH 0/8] Introduce fwctl subystem
Fri, Jun 07, 2024 at 05:14:51PM CEST, jgg@...dia.com wrote:
>On Fri, Jun 07, 2024 at 08:50:17AM -0600, David Ahern wrote:
>
>> Mellanox offers both with the Spectrum line and should have a pretty
>> good understanding of how many customers deploy with the SDK vs
>> switchdev. Why is that?
>
>We offer lots of options with mlx5 switching too, and switchdev is not
>being selected by customers principally for performance reasons, in my
>view.
>
>The OVS space wants to operate the switch much like a firewall and
>this creates a high rate of database updates and exception
>packets. DPDK can operate all the same offload HW from userspace and
>avoid all the system call and other kernel overhead. It is much more
>purpose built to what OVS wants to do. In the >50Gbps space this
>matters a lot and overall DPDK performance notably wins over switchdev
>for many OVS workloads - even though the high speed path is
>near-identical.
>
>In this role DPDK is effectively a switch SDK, an open source one at
>least.
>
>Sadly I'm seeing signs that proprietary OVS focused SDKs (think
>various P4 offerings and others) are out competing open DPDK on
>merit :(
>
>For whatever reason the market for switching is not strongly motivated
>toward open SDKs, and the available open solutions are struggling a
>bit to compete.
>
>But to repeat again, fwctl is not for dataplane, it is not for
>implementing a switch SDK (go use RDMA if you want to do that). I will
switch sdk is all about control plane.
>write here a commitment to accept patches blocking such usages if
>drivers try to abuse the purpose of the subsystem.
>
>Jason
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