On 10/9/24 00:10, Joe Damato wrote:
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/ ?
io_uring man pages would need to be updated with it, there are tests
in liburing and would be a good idea to add back a simple exapmle
to liburing/example/*. I think it should cover it
--
Pavel Begunkov
