[PATCHSET v6 0/3] Add support for ring mapped provided buffers

[Jens Axboe <axboe@kernel.dk>]

Hi,

This series builds to adding support for a different way of doing
provided buffers, which is a lot more efficient than the existing scheme
for high rate of consumption/provision of buffers. The interesting bits
here are patch 3, which also has some performance numbers an an
explanation of it.

Patch 1 adds NOP support for provided buffers, just so that we can
benchmark the last change.

Patch 2 just abstracts out the pinning code.

Patch 3 adds the actual feature.

This passes the full liburing suite, and various test cases I adopted
to use ring provided buffers.

v6:
- Change layout so that 'head' overlaps with reserved field in first
  buffer, avoiding the weird split of first page having N-1 buffers and
  the rest N (Dylan)
- Rebase on current kernel bits
- Fix missing ring unlock on out-of-bufs
- Fix issue in io_recv()

Can also be found in my git repo, for-5.19/io_uring-pbuf branch:

https://git.kernel.dk/cgit/linux-block/log/?h=for-5.19/io_uring-pbuf

and there's an associated liburing branch too:

https://git.kernel.dk/cgit/liburing/log/?h=huge

 fs/io_uring.c                 | 323 +++++++++++++++++++++++++++++-----
 include/uapi/linux/io_uring.h |  36 ++++
 2 files changed, 319 insertions(+), 40 deletions(-)

-- 
Jens Axboe