netdev - Re: [PATCH v1 00/15] io

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Message-ID: <ZwW7_cRr_UpbEC-X@LQ3V64L9R2>
Date: Tue, 8 Oct 2024 16:10:53 -0700
From: Joe Damato <jdamato@...tly.com>
To: David Wei <dw@...idwei.uk>
Cc: io-uring@...r.kernel.org, netdev@...r.kernel.org,
	Jens Axboe <axboe@...nel.dk>,
	Pavel Begunkov <asml.silence@...il.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	David Ahern <dsahern@...nel.org>,
	Mina Almasry <almasrymina@...gle.com>
Subject: Re: [PATCH v1 00/15] io_uring zero copy rx

On Mon, Oct 07, 2024 at 03:15:48PM -0700, David Wei wrote:
> This patchset adds support for zero copy rx into userspace pages using
> io_uring, eliminating a kernel to user copy.
> 
> We configure a page pool that a driver uses to fill a hw rx queue to
> hand out user pages instead of kernel pages. Any data that ends up
> hitting this hw rx queue will thus be dma'd into userspace memory
> directly, without needing to be bounced through kernel memory. 'Reading'
> data out of a socket instead becomes a _notification_ mechanism, where
> the kernel tells userspace where the data is. The overall approach is
> similar to the devmem TCP proposal.
> 
> This relies on hw header/data split, flow steering and RSS to ensure
> packet headers remain in kernel memory and only desired flows hit a hw
> rx queue configured for zero copy. Configuring this is outside of the
> scope of this patchset.

This looks super cool and very useful, thanks for doing this work.

Is there any possibility of some notes or sample pseudo code on how
userland can use this being added to Documentation/networking/ ?