On 2024-10-09 09:12, Jens Axboe wrote: > On 10/9/24 9:07 AM, Pavel Begunkov wrote: >> 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 > > man pages for sure, but +1 to the example too. Just a basic thing would > get the point across, I think. > Yeah, there's the liburing side with helpers and all that which will get manpages. We'll also put back a simple example demonstrating the uAPI. The liburing changes will be sent as a separate patchset to the io-uring list.
