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Introduce a socket-specific io_uring_cmd to support
getsockname/getpeername via io_uring. I made this an io_uring_cmd
instead of a new operation to avoid polluting the command namespace with
what is exclusively a socket operation. In addition, since we don't
need to conform to existing interfaces, this merges the
getsockname/getpeername in a single operation, since the implementation
is pretty much the same.
This has been frequently requested, for instance at [1] and more
recently in the project Discord channel. The main use-case is to support
fixed socket file descriptors.
[1] https://github.com/axboe/liburing/issues/1356
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add a way to share an ifq from a src ring that is real (i.e. bound to a
HW RX queue) with other rings. This is done by passing a new flag
IORING_ZCRX_IFQ_REG_IMPORT in the registration struct
io_uring_zcrx_ifq_reg, alongside the fd of an exported zcrx ifq.
Signed-off-by: David Wei <dw@davidwei.uk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add an option to wrap a zcrx instance into a file and expose it to the
user space. Currently, users can't do anything meaningful with the file,
but it'll be used in a next patch to import it into another io_uring
instance. It's implemented as a new op called ZCRX_CTRL_EXPORT for the
IORING_REGISTER_ZCRX_CTRL registration opcode.
Signed-off-by: David Wei <dw@davidwei.uk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add an zcrx interface via IORING_REGISTER_ZCRX_CTRL that forces the
kernel to flush / consume entries from the refill queue. Just as with
the IORING_REGISTER_ZCRX_REFILL attempt, the motivation is to address
cases where the refill queue becomes full, and the user can't return
buffers and needs to stash them. It's still a slow path, and the user
should size refill queue appropriately, but it should be helpful for
handling temporary traffic spikes and other unpredictable conditions.
The interface is simpler comparing to ZCRX_REFILL as it doesn't need
temporary refill entry arrays and gives natural batching, whereas
ZCRX_REFILL requires even more user logic to be somewhat efficient.
Also, add a structure for the operation. It's not currently used but
can serve for future improvements like limiting the number of buffers to
process, etc.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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It'll be annoying and take enough of boilerplate code to implement
new zcrx features as separate io_uring register opcode. Introduce
IORING_REGISTER_ZCRX_CTRL that will multiplex such calls to zcrx.
Note, there are no real users of the opcode in this patch.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge 6.18-rc io_uring fixes, as certain coming changes depend on some
of these.
* io_uring-6.18:
io_uring/rsrc: don't use blk_rq_nr_phys_segments() as number of bvecs
io_uring/query: return number of available queries
io_uring/rw: ensure allocated iovec gets cleared for early failure
io_uring: fix regbuf vector size truncation
io_uring: fix types for region size calulation
io_uring/zcrx: remove sync refill uapi
io_uring: fix buffer auto-commit for multishot uring_cmd
io_uring: correct __must_hold annotation in io_install_fixed_file
io_uring zcrx: add MAINTAINERS entry
io_uring: Fix code indentation error
io_uring/sqpoll: be smarter on when to update the stime usage
io_uring/sqpoll: switch away from getrusage() for CPU accounting
io_uring: fix incorrect unlikely() usage in io_waitid_prep()
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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There is a better way to handle the problem IORING_REGISTER_ZCRX_REFILL
solves. The uapi can also be slightly adjusted to accommodate future
extensions. Remove the feature for now, it'll be reworked for the next
release.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Normal rings support 64b SQEs for posting submissions, while certain
features require the ring to be configured with IORING_SETUP_SQE128, as
they need to convey more information per submission. This, in turn,
makes ALL the SQEs be 128b in size. This is somewhat wasteful and
inefficient, particularly when only certain SQEs need to be of the
bigger variant.
This adds support for setting up a ring with mixed SQE sizes, using
IORING_SETUP_SQE_MIXED. When setup in this mode, SQEs posted to the ring
may be either 64b or 128b in size. If a SQE is 128b in size, then opcode
will be set to a variante to indicate that this is the case. Any other
non-128b opcode will assume the SQ's default size.
SQEs on these types of mixed rings may also utilize NOP with skip
success set. This can happen if the ring is one (small) SQE entry away
from wrapping, and an attempt is made to get a 128b SQE. As SQEs must be
contiguous in the SQ ring, a 128b SQE cannot wrap the ring. For this
case, a single NOP SQE should be inserted with the SKIP_SUCCESS flag
set. The kernel will process this as a normal NOP and without posting a
CQE.
Signed-off-by: Keith Busch <kbusch@kernel.org>
[axboe: {} style fix and assign sqe before opcode read]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Be consistent with tab style of "liburing/src/include/liburing/io_uring.h".
Signed-off-by: Haiyue Wang <haiyuewa@163.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Returning buffers via a ring is performant and convenient, but it
becomes a problem when/if the user misconfigured the ring size and it
becomes full. Add a synchronous way to return buffers back to the page
pool via a new register opcode. It's supposed to be a reliable slow
path for refilling.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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There are many parameters users might want to query about io_uring like
available request types or the ring sizes. This patch introduces an
interface for such slow path queries.
It was written with several requirements in mind:
- Can be used with or without an io_uring instance. Asking for supported
setup flags before creating an instance as well as qeurying info about
an already created ring are valid use cases.
- Should be moderately fast. For example, users might use it to
periodically retrieve ring attributes at runtime. As a consequence,
it should be able to query multiple attributes in a single syscall.
- Backward and forward compatible.
- Should be reasobably easy to use.
- Reduce the kernel code size for introducing new query types.
It's implemented as a new registration opcode IORING_REGISTER_QUERY.
The user passes one or more query strutctures linked together, each
represented by struct io_uring_query_hdr. The header stores common
control fields needed for processing and points to query type specific
information.
The header contains
- The query type
- The result field, which on return contains the error code for the query
- Pointer to the query type specific information
- The size of the query structure. The kernel will only populate up to
the size, which helps with backward compatibility. The kernel can also
reduce the size, so if the current kernel is older than the inteface
the user tries to use, it'll get only the supported bits.
- next_entry field is used to chain multiple queries.
Apart from common registeration syscall failures, it can only immediately
return an error code in case when the headers are incorrect or any
other addresses and invalid. That usually mean that the userspace
doesn't use the API right and should be corrected. All query type
specific errors are returned in the header's result field.
As an example, the patch adds a single query type for now, i.e.
IO_URING_QUERY_OPCODES, which tells what register / request / etc.
opcodes are supported, but there are particular plans to extend it.
Note: there is a request probing interface via IORING_REGISTER_PROBE,
but it's a mess. It requires the user to create a ring first, it only
works for requests, and requires dynamic allocations.
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This adds support for setting IORING_NOP_CQE32 as a flag for a NOP
command, in which case a 32b CQE will be posted rather than a regular
one. This is the default if the ring has been setup with
IORING_SETUP_CQE32. If the ring has been setup with
IORING_SETUP_CQE_MIXED, then 16b CQEs will be posted without this flag
set, and 32b CQEs if this flag is set. For the latter case, sqe->off is
what will be posted as cqe->big_cqe[0] and sqe->addr is what will be
posted as cqe->big_cqe[1].
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Normal rings support 16b CQEs for posting completions, while certain
features require the ring to be configured with IORING_SETUP_CQE32, as
they need to convey more information per completion. This, in turn,
makes ALL the CQEs be 32b in size. This is somewhat wasteful and
inefficient, particularly when only certain CQEs need to be of the
bigger variant.
This adds support for setting up a ring with mixed CQE sizes, using
IORING_SETUP_CQE_MIXED. When setup in this mode, CQEs posted to the ring
may be either 16b or 32b in size. If a CQE is 32b in size, then
IORING_CQE_F_32 is set in the CQE flags to indicate that this is the
case. If this flag isn't set, the CQE is the normal 16b variant.
CQEs on these types of mixed rings may also have IORING_CQE_F_SKIP set.
This can happen if the ring is one (small) CQE entry away from wrapping,
and an attempt is made to post a 32b CQE. As CQEs must be contigious in
the CQ ring, a 32b CQE cannot wrap the ring. For this case, a single
dummy CQE is posted with the SKIP flag set. The application should
simply ignore those.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This adds the CQE flags related to supporting a mixed CQ ring mode, where
both normal (16b) and big (32b) CQEs may be posted.
No functional changes in this patch.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add UAPI flag IORING_URING_CMD_MULTISHOT for supporting multishot
uring_cmd operations with provided buffer.
This enables drivers to post multiple completion events from a single
uring_cmd submission, which is useful for:
- Notifying userspace of device events (e.g., interrupt handling)
- Supporting devices with multiple event sources (e.g., multi-queue devices)
- Avoiding the need for device poll() support when events originate
from multiple sources device-wide
The implementation adds two new APIs:
- io_uring_cmd_select_buffer(): selects a buffer from the provided
buffer group for multishot uring_cmd
- io_uring_mshot_cmd_post_cqe(): posts a CQE after event data is
pushed to the provided buffer
Multishot uring_cmd must be used with buffer select (IOSQE_BUFFER_SELECT)
and is mutually exclusive with IORING_URING_CMD_FIXED for now.
The ublk driver will be the first user of this functionality:
https://github.com/ming1/linux/commits/ublk-devel/
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250821040210.1152145-3-ming.lei@redhat.com
[axboe: fold in fix for !CONFIG_IO_URING]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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At the moment you have to use sendmsg for vectorized send.
While this works it's suboptimal as it also means you need to
allocate a struct msghdr that needs to be kept alive until a
submission happens. We can remove this limitation by just
allowing to use send directly.
Signed-off-by: Norman Maurer <norman_maurer@apple.com>
Link: https://lore.kernel.org/r/20250729065952.26646-1-norman_maurer@apple.com
[axboe: remove -EINVAL return for SENDMSG and SEND_VECTORIZED]
[axboe: allow send_zc to set SEND_VECTORIZED too]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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__kernel_rwf_t is defined as int, the actual size of which is
implementation defined. It won't go well if some compiler / archs
ever defines it as i64, so replace it with __u32, hoping that
there is no one using i16 for it.
Cc: stable@vger.kernel.org
Fixes: 2b188cc1bb857 ("Add io_uring IO interface")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/47c666c4ee1df2018863af3a2028af18feef11ed.1751412511.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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An errant ';' slipped into that definition, which will cause some
compilers to complain when it's used in an application:
timestamp.c:257:45: error: empty expression statement has no effect; remove unnecessary ';' to silence this warning [-Werror,-Wextra-semi-stmt]
257 | hwts = cqe->flags & IORING_CQE_F_TSTAMP_HW;
| ^
Fixes: 9e4ed359b8ef ("io_uring/netcmd: add tx timestamping cmd support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add a new socket command which returns tx time stamps to the user. It
provide an alternative to the existing error queue recvmsg interface.
The command works in a polled multishot mode, which means io_uring will
poll the socket and keep posting timestamps until the request is
cancelled or fails in any other way (e.g. with no space in the CQ). It
reuses the net infra and grabs timestamps from the socket's error queue.
The command requires IORING_SETUP_CQE32. All non-final CQEs (marked with
IORING_CQE_F_MORE) have cqe->res set to the tskey, and the upper 16 bits
of cqe->flags keep tstype (i.e. offset by IORING_CQE_BUFFER_SHIFT). The
timevalue is store in the upper part of the extended CQE. The final
completion won't have IORING_CQE_F_MORE and will have cqe->res storing
0/error.
Suggested-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/92ee66e6b33b8de062a977843d825f58f21ecd37.1750065793.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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To test and profile the overhead of io_uring task_work and the various
types of it, add IORING_NOP_TW which tells nop to signal completions
through task_work rather than complete them inline.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pull io_uring updates from Jens Axboe:
- Avoid indirect function calls in io-wq for executing and freeing
work.
The design of io-wq is such that it can be a generic mechanism, but
as it's just used by io_uring now, may as well avoid these indirect
calls
- Clean up registered buffers for networking
- Add support for IORING_OP_PIPE. Pretty straight forward, allows
creating pipes with io_uring, particularly useful for having these be
instantiated as direct descriptors
- Clean up the coalescing support fore registered buffers
- Add support for multiple interface queues for zero-copy rx
networking. As this feature was merged for 6.15 it supported just a
single ifq per ring
- Clean up the eventfd support
- Add dma-buf support to zero-copy rx
- Clean up and improving the request draining support
- Clean up provided buffer support, most notably with an eye toward
making the legacy support less intrusive
- Minor fdinfo cleanups, dropping support for dumping what credentials
are registered
- Improve support for overflow CQE handling, getting rid of GFP_ATOMIC
for allocating overflow entries where possible
- Improve detection of cases where io-wq doesn't need to spawn a new
worker unnecessarily
- Various little cleanups
* tag 'for-6.16/io_uring-20250523' of git://git.kernel.dk/linux: (59 commits)
io_uring/cmd: warn on reg buf imports by ineligible cmds
io_uring/io-wq: only create a new worker if it can make progress
io_uring/io-wq: ignore non-busy worker going to sleep
io_uring/io-wq: move hash helpers to the top
trace/io_uring: fix io_uring_local_work_run ctx documentation
io_uring: finish IOU_OK -> IOU_COMPLETE transition
io_uring: add new helpers for posting overflows
io_uring: pass in struct io_big_cqe to io_alloc_ocqe()
io_uring: make io_alloc_ocqe() take a struct io_cqe pointer
io_uring: split alloc and add of overflow
io_uring: open code io_req_cqe_overflow()
io_uring/fdinfo: get rid of dumping credentials
io_uring/fdinfo: only compile if CONFIG_PROC_FS is set
io_uring/kbuf: unify legacy buf provision and removal
io_uring/kbuf: refactor __io_remove_buffers
io_uring/kbuf: don't compute size twice on prep
io_uring/kbuf: drop extra vars in io_register_pbuf_ring
io_uring/kbuf: use mem_is_zero()
io_uring/kbuf: account ring io_buffer_list memory
io_uring: drain based on allocates reqs
...
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Add support for dmabuf backed zcrx areas. To use it, the user should
pass IORING_ZCRX_AREA_DMABUF in the struct io_uring_zcrx_area_reg flags
field and pass a dmabuf fd in the dmabuf_fd field.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20bb1890e60a82ec945ab36370d1fd54be414ab6.1746097431.git.asml.silence@gmail.com
Link: https://lore.kernel.org/io-uring/6e37db97303212bbd8955f9501cf99b579f8aece.1746547722.git.asml.silence@gmail.com
[axboe: fold in fixup]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Allow userspace to pass a per-I/O write stream in the SQE:
__u8 write_stream;
The __u8 type matches the size the filesystems and block layer support.
Application can query the supported values from the block devices
max_write_streams sysfs attribute. Unsupported values are ignored by
file operations that do not support write streams or rejected with an
error by those that support them.
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-7-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This works just like pipe2(2), except it also supports fixed file
descriptors. Used in a similar fashion as for other fd instantiating
opcodes (like accept, socket, open, etc), where sqe->file_slot is set
appropriately if two direct descriptors are desired rather than a set
of normal file descriptors.
sqe->addr must be set to a pointer to an array of 2 integers, which
is where the fixed/normal file descriptors are copied to.
sqe->pipe_flags contains flags, same as what is allowed for pipe2(2).
Future expansion of per-op private flags can go in sqe->ioprio,
like we do for other opcodes that take both a "syscall" flag set and
an io_uring opcode specific flag set.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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IORING_OP_RECV_ZC requests take a zcrx object id via sqe::zcrx_ifq_idx,
which binds it to the corresponding if / queue. However, we don't return
that id back to the user. It's fine as currently there can be only one
zcrx and the user assumes that its id should be 0, but as we'll need
multiple zcrx objects in the future let's explicitly pass it back on
registration.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8714667d370651962f7d1a169032e5f02682a73e.1744722517.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pull more io_uring updates from Jens Axboe:
"Final separate updates for io_uring.
This started out as a series of cleanups improvements and improvements
for registered buffers, but as the last series of the io_uring changes
for 6.15, it also collected a few fixes for the other branches on top:
- Add support for vectored fixed/registered buffers.
Previously only single segments have been supported for commands,
now vectored variants are supported as well. This series includes
networking and file read/write support.
- Small series unifying return codes across multi and single shot.
- Small series cleaning up registerd buffer importing.
- Adding support for vectored registered buffers for uring_cmd.
- Fix for io-wq handling of command reissue.
- Various little fixes and tweaks"
* tag 'for-6.15/io_uring-reg-vec-20250327' of git://git.kernel.dk/linux: (25 commits)
io_uring/net: fix io_req_post_cqe abuse by send bundle
io_uring/net: use REQ_F_IMPORT_BUFFER for send_zc
io_uring: move min_events sanitisation
io_uring: rename "min" arg in io_iopoll_check()
io_uring: open code __io_post_aux_cqe()
io_uring: defer iowq cqe overflow via task_work
io_uring: fix retry handling off iowq
io_uring/net: only import send_zc buffer once
io_uring/cmd: introduce io_uring_cmd_import_fixed_vec
io_uring/cmd: add iovec cache for commands
io_uring/cmd: don't expose entire cmd async data
io_uring: rename the data cmd cache
io_uring: rely on io_prep_reg_vec for iovec placement
io_uring: introduce io_prep_reg_iovec()
io_uring: unify STOP_MULTISHOT with IOU_OK
io_uring: return -EAGAIN to continue multishot
io_uring: cap cached iovec/bvec size
io_uring/net: implement vectored reg bufs for zctx
io_uring/net: convert to struct iou_vec
io_uring/net: pull vec alloc out of msghdr import
...
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Pull io_uring epoll support from Jens Axboe:
"This adds support for reading epoll events via io_uring.
While this may seem counter-intuitive (and/or productive), the
reasoning here is that quite a few existing epoll event loops can
easily do a partial conversion to a completion based model, but are
still stuck with one (or few) event types that remain readiness based.
For that case, they then need to add the io_uring fd to the epoll
context, and continue to rely on epoll_wait(2) for waiting on events.
This misses out on the finer grained waiting that io_uring can do, to
reduce context switches and wait for multiple events in one batch
reliably.
With adding support for reaping epoll events via io_uring, the whole
legacy readiness based event types can still be reaped via epoll, with
the overall waiting in the loop be driven by io_uring"
* tag 'for-6.15/io_uring-epoll-wait-20250325' of git://git.kernel.dk/linux:
io_uring/epoll: add support for IORING_OP_EPOLL_WAIT
io_uring/epoll: remove CONFIG_EPOLL guards
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Pull io_uring zero-copy receive support from Jens Axboe:
"This adds support for zero-copy receive with io_uring, enabling fast
bulk receive of data directly into application memory, rather than
needing to copy the data out of kernel memory.
While this version only supports host memory as that was the initial
target, other memory types are planned as well, with notably GPU
memory coming next.
This work depends on some networking components which were queued up
on the networking side, but have now landed in your tree.
This is the work of Pavel Begunkov and David Wei. From the v14 posting:
'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.
We share netdev core infra with devmem TCP. The main difference is
that io_uring is used for the uAPI and the lifetime of all objects
are bound to an io_uring instance. Data is 'read' using a new
io_uring request type. When done, data is returned via a new shared
refill queue. A zero copy page pool refills a hw rx queue from this
refill queue directly. Of course, the lifetime of these data
buffers are managed by io_uring rather than the networking stack,
with different refcounting rules.
This patchset is the first step adding basic zero copy support. We
will extend this iteratively with new features e.g. dynamically
allocated zero copy areas, THP support, dmabuf support, improved
copy fallback, general optimisations and more'
In a local setup, I was able to saturate a 200G link with a single CPU
core, and at netdev conf 0x19 earlier this month, Jamal reported
188Gbit of bandwidth using a single core (no HT, including soft-irq).
Safe to say the efficiency is there, as bigger links would be needed
to find the per-core limit, and it's considerably more efficient and
faster than the existing devmem solution"
* tag 'for-6.15/io_uring-rx-zc-20250325' of git://git.kernel.dk/linux:
io_uring/zcrx: add selftest case for recvzc with read limit
io_uring/zcrx: add a read limit to recvzc requests
io_uring: add missing IORING_MAP_OFF_ZCRX_REGION in io_uring_mmap
io_uring: Rename KConfig to Kconfig
io_uring/zcrx: fix leaks on failed registration
io_uring/zcrx: recheck ifq on shutdown
io_uring/zcrx: add selftest
net: add documentation for io_uring zcrx
io_uring/zcrx: add copy fallback
io_uring/zcrx: throttle receive requests
io_uring/zcrx: set pp memory provider for an rx queue
io_uring/zcrx: add io_recvzc request
io_uring/zcrx: dma-map area for the device
io_uring/zcrx: implement zerocopy receive pp memory provider
io_uring/zcrx: grab a net device
io_uring/zcrx: add io_zcrx_area
io_uring/zcrx: add interface queue and refill queue
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By default, io_uring marks a waiting task as being in iowait, if it's
sleeping waiting on events and there are pending requests. This isn't
necessarily always useful, and may be confusing on non-storage setups
where iowait isn't expected. It can also cause extra power usage, by
preventing the CPU from entering lower sleep states.
This adds a new enter flag, IORING_ENTER_NO_IOWAIT. If set, then
io_uring will not account the sleeping task as being in iowait. If the
kernel supports this feature, then it will be marked by having the
IORING_FEAT_NO_IOWAIT feature flag set.
As the kernel currently does not support separating the iowait
accounting and CPU frequency boosting, the IORING_ENTER_NO_IOWAIT
controls both of these at the same time. In the future, if those do end
up being split, then it'd be possible to control them separately.
However, it seems more likely that the kernel will decouple iowait and
CPU frequency boosting anyway.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Implement registered buffer vectored reads with new opcodes
IORING_OP_WRITEV_FIXED and IORING_OP_READV_FIXED.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d7c89eb481e870f598edc91cc66ff4d1e4ae3788.1741362889.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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* for-6.15/io_uring-epoll-wait:
io_uring/epoll: add support for IORING_OP_EPOLL_WAIT
io_uring/epoll: remove CONFIG_EPOLL guards
eventpoll: add epoll_sendevents() helper
eventpoll: abstract out ep_try_send_events() helper
eventpoll: abstract out parameter sanity checking
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* for-6.15/io_uring-rx-zc: (80 commits)
io_uring/zcrx: add selftest case for recvzc with read limit
io_uring/zcrx: add a read limit to recvzc requests
io_uring: add missing IORING_MAP_OFF_ZCRX_REGION in io_uring_mmap
io_uring: Rename KConfig to Kconfig
io_uring/zcrx: fix leaks on failed registration
io_uring/zcrx: recheck ifq on shutdown
io_uring/zcrx: add selftest
net: add documentation for io_uring zcrx
io_uring/zcrx: add copy fallback
io_uring/zcrx: throttle receive requests
io_uring/zcrx: set pp memory provider for an rx queue
io_uring/zcrx: add io_recvzc request
io_uring/zcrx: dma-map area for the device
io_uring/zcrx: implement zerocopy receive pp memory provider
io_uring/zcrx: grab a net device
io_uring/zcrx: add io_zcrx_area
io_uring/zcrx: add interface queue and refill queue
net: add helpers for setting a memory provider on an rx queue
net: page_pool: add memory provider helpers
net: prepare for non devmem TCP memory providers
...
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For existing epoll event loops that can't fully convert to io_uring,
the used approach is usually to add the io_uring fd to the epoll
instance and use epoll_wait() to wait on both "legacy" and io_uring
events. While this work, it isn't optimal as:
1) epoll_wait() is pretty limited in what it can do. It does not support
partial reaping of events, or waiting on a batch of events.
2) When an io_uring ring is added to an epoll instance, it activates the
io_uring "I'm being polled" logic which slows things down.
Rather than use this approach, with EPOLL_WAIT support added to io_uring,
event loops can use the normal io_uring wait logic for everything, as
long as an epoll wait request has been armed with io_uring.
Note that IORING_OP_EPOLL_WAIT does NOT take a timeout value, as this
is an async request. Waiting on io_uring events in general has various
timeout parameters, and those are the ones that should be used when
waiting on any kind of request. If events are immediately available for
reaping, then This opcode will return those immediately. If none are
available, then it will post an async completion when they become
available.
cqe->res will contain either an error code (< 0 value) for a malformed
request, invalid epoll instance, etc. It will return a positive result
indicating how many events were reaped.
IORING_OP_EPOLL_WAIT requests may be canceled using the normal io_uring
cancelation infrastructure.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This is obviously not that important, but when changes are synced back
from the kernel to liburing, the codespell CI ends up erroring because
of this misspelling. Let's just correct it and avoid this biting us
again on an import.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add io_uring opcode OP_RECV_ZC for doing zero copy reads out of a
socket. Only the connection should be land on the specific rx queue set
up for zero copy, and the socket must be handled by the io_uring
instance that the rx queue was registered for zero copy with. That's
because neither net_iovs / buffers from our queue can be read by outside
applications, nor zero copy is possible if traffic for the zero copy
connection goes to another queue. This coordination is outside of the
scope of this patch series. Also, any traffic directed to the zero copy
enabled queue is immediately visible to the application, which is why
CAP_NET_ADMIN is required at the registration step.
Of course, no data is actually read out of the socket, it has already
been copied by the netdev into userspace memory via DMA. OP_RECV_ZC
reads skbs out of the socket and checks that its frags are indeed
net_iovs that belong to io_uring. A cqe is queued for each one of these
frags.
Recall that each cqe is a big cqe, with the top half being an
io_uring_zcrx_cqe. The cqe res field contains the len or error. The
lower IORING_ZCRX_AREA_SHIFT bits of the struct io_uring_zcrx_cqe::off
field contain the offset relative to the start of the zero copy area.
The upper part of the off field is trivially zero, and will be used
to carry the area id.
For now, there is no limit as to how much work each OP_RECV_ZC request
does. It will attempt to drain a socket of all available data. This
request always operates in multishot mode.
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: David Wei <dw@davidwei.uk>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20250215000947.789731-7-dw@davidwei.uk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add io_zcrx_area that represents a region of userspace memory that is
used for zero copy. During ifq registration, userspace passes in the
uaddr and len of userspace memory, which is then pinned by the kernel.
Each net_iov is mapped to one of these pages.
The freelist is a spinlock protected list that keeps track of all the
net_iovs/pages that aren't used.
For now, there is only one area per ifq and area registration happens
implicitly as part of ifq registration. There is no API for
adding/removing areas yet. The struct for area registration is there for
future extensibility once we support multiple areas and TCP devmem.
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20250215000947.789731-3-dw@davidwei.uk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add a new object called an interface queue (ifq) that represents a net
rx queue that has been configured for zero copy. Each ifq is registered
using a new registration opcode IORING_REGISTER_ZCRX_IFQ.
The refill queue is allocated by the kernel and mapped by userspace
using a new offset IORING_OFF_RQ_RING, in a similar fashion to the main
SQ/CQ. It is used by userspace to return buffers that it is done with,
which will then be re-used by the netdev again.
The main CQ ring is used to notify userspace of received data by using
the upper 16 bytes of a big CQE as a new struct io_uring_zcrx_cqe. Each
entry contains the offset + len to the data.
For now, each io_uring instance only has a single ifq.
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: David Wei <dw@davidwei.uk>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20250215000947.789731-2-dw@davidwei.uk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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After commit 9a213d3b80c0, we can pass additional attributes along with
read/write. However, userspace doesn't know that. Add a new feature flag
IORING_FEAT_RW_ATTR, to notify the userspace that the kernel has this
ability.
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Li Zetao <lizetao1@huawei.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Tested-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20241205062109.1788-1-anuj20.g@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add the ability to pass additional attributes along with read/write.
Application can prepare attibute specific information and pass its
address using the SQE field:
__u64 attr_ptr;
Along with setting a mask indicating attributes being passed:
__u64 attr_type_mask;
Overall 64 attributes are allowed and currently one attribute
'IORING_RW_ATTR_FLAG_PI' is supported.
With PI attribute, userspace can pass following information:
- flags: integrity check flags IO_INTEGRITY_CHK_{GUARD/APPTAG/REFTAG}
- len: length of PI/metadata buffer
- addr: address of metadata buffer
- seed: seed value for reftag remapping
- app_tag: application defined 16b value
Process this information to prepare uio_meta_descriptor and pass it down
using kiocb->private.
PI attribute is supported only for direct IO.
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20241128112240.8867-7-anuj20.g@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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A separate wait argument registration API was removed, also delete
leftover uapi definitions.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/143b6a53591badac23632d3e6fa3e5db4b342ee2.1731942445.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Now we've got a more generic region registration API, place
IORING_ENTER_EXT_ARG_REG and re-enable it.
First, the user has to register a region with the
IORING_MEM_REGION_REG_WAIT_ARG flag set. It can only be done for a
ring in a disabled state, aka IORING_SETUP_R_DISABLED, to avoid races
with already running waiters. With that we should have stable constant
values for ctx->cq_wait_{size,arg} in io_get_ext_arg_reg() and hence no
READ_ONCE required.
The other API difference is that we're now passing byte offsets instead
of indexes. The user _must_ align all offsets / pointers to the native
word size, failing to do so might but not necessarily has to lead to a
failure usually returned as -EFAULT. liburing will be hiding this
details from users.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/81822c1b4ffbe8ad391b4f9ad1564def0d26d990.1731689588.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Regions will serve multiple purposes. First, with it we can decouple
ring/etc. object creation from registration / mapping of the memory they
will be placed in. We already have hacks that allow to put both SQ and
CQ into the same huge page, in the future we should be able to:
region = create_region(io_ring);
create_pbuf_ring(io_uring, region, offset=0);
create_pbuf_ring(io_uring, region, offset=N);
The second use case is efficiently passing parameters. The following
patch enables back on top of regions IORING_ENTER_EXT_ARG_REG, which
optimises wait arguments. It'll also be useful for request arguments
replacing iovecs, msghdr, etc. pointers. Eventually it would also be
handy for BPF as well if it comes to fruition.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0798cf3a14fad19cfc96fc9feca5f3e11481691d.1731689588.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We've got a good number of mappings we share with the userspace, that
includes the main rings, provided buffer rings, upcoming rings for
zerocopy rx and more. All of them duplicate user argument parsing and
some internal details as well (page pinnning, huge page optimisations,
mmap'ing, etc.)
Introduce a notion of regions. For userspace for now it's just a new
structure called struct io_uring_region_desc which is supposed to
parameterise all such mapping / queue creations. A region either
represents a user provided chunk of memory, in which case the user_addr
field should point to it, or a request for the kernel to allocate the
memory, in which case the user would need to mmap it after using the
offset returned in the mmap_offset field. With a uniform userspace API
we can avoid additional boiler plate code and apply future optimisation
to all of them at once.
Internally, there is a new structure struct io_mapped_region holding all
relevant runtime information and some helpers to work with it. This
patch limits it to user provided regions.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0e6fe25818dfbaebd1bd90b870a6cac503fe1a24.1731689588.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Disable wait argument registration as it'll be replaced with a more
generic feature. We'll still need IORING_ENTER_EXT_ARG_REG parsing
in a few commits so leave it be.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/70b1d1d218c41ba77a76d1789c8641dab0b0563e.1731689588.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add the static napi tracking strategy. That allows the user to manually
manage the napi ids list for busy polling, and eliminate the overhead of
dynamically updating the list from the fast path.
Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Link: https://lore.kernel.org/r/96943de14968c35a5c599352259ad98f3c0770ba.1728828877.git.olivier@trillion01.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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A new hybrid poll is implemented on the io_uring layer. Once an IO is
issued, it will not poll immediately, but rather block first and re-run
before IO complete, then poll to reap IO. While this poll method could
be a suboptimal solution when running on a single thread, it offers
performance lower than regular polling but higher than IRQ, and CPU
utilization is also lower than polling.
To use hybrid polling, the ring must be setup with both the
IORING_SETUP_IOPOLL and IORING_SETUP_HYBRID)IOPOLL flags set. Hybrid
polling has the same restrictions as IOPOLL, in that commands must
explicitly support it.
Signed-off-by: hexue <xue01.he@samsung.com>
Link: https://lore.kernel.org/r/20241101091957.564220-2-xue01.he@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Currently cloning a buffer table will fail if the destination already has
a table. But it should be possible to use it to replace existing elements.
Add a IORING_REGISTER_DST_REPLACE cloning flag, which if set, will allow
the destination to already having a buffer table. If that is the case,
then entries designated by offset + nr buffers will be replaced if they
already exist.
Note that it's allowed to use IORING_REGISTER_DST_REPLACE and not have
an existing table, in which case it'll work just like not having the
flag set and an empty table - it'll just assign the newly created table
for that case.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Right now buffer cloning is an all-or-nothing kind of thing - either the
whole table is cloned from a source to a destination ring, or nothing at
all.
However, it's not always desired to clone the whole thing. Allow for
the application to specify a source and destination offset, and a
number of buffers to clone. If the destination offset is non-zero, then
allocate sparse nodes upfront.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Useful for testing performance/efficiency impact of registered files
and buffers, vs (particularly) non-registered files.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Generally applications have 1 or a few waits of waiting, yet they pass
in a struct io_uring_getevents_arg every time. This needs to get copied
and, in turn, the timeout value needs to get copied.
Rather than do this for every invocation, allow the application to
register a fixed set of wait regions that can simply be indexed when
asking the kernel to wait on events.
At ring setup time, the application can register a number of these wait
regions and initialize region/index 0 upfront:
struct io_uring_reg_wait *reg;
reg = io_uring_setup_reg_wait(ring, nr_regions, &ret);
/* set timeout and mark as set, sigmask/sigmask_sz as needed */
reg->ts.tv_sec = 0;
reg->ts.tv_nsec = 100000;
reg->flags = IORING_REG_WAIT_TS;
where nr_regions >= 1 && nr_regions <= PAGE_SIZE / sizeof(*reg). The
above initializes index 0, but 63 other regions can be initialized,
if needed. Now, instead of doing:
struct __kernel_timespec timeout = { .tv_nsec = 100000, };
io_uring_submit_and_wait_timeout(ring, &cqe, nr, &t, NULL);
to wait for events for each submit_and_wait, or just wait, operation, it
can just reference the above region at offset 0 and do:
io_uring_submit_and_wait_reg(ring, &cqe, nr, 0);
to achieve the same goal of waiting 100usec without needing to copy
both struct io_uring_getevents_arg (24b) and struct __kernel_timeout
(16b) for each invocation. Struct io_uring_reg_wait looks as follows:
struct io_uring_reg_wait {
struct __kernel_timespec ts;
__u32 min_wait_usec;
__u32 flags;
__u64 sigmask;
__u32 sigmask_sz;
__u32 pad[3];
__u64 pad2[2];
};
embedding the timeout itself in the region, rather than passing it as
a pointer as well. Note that the signal mask is still passed as a
pointer, both for compatability reasons, but also because there doesn't
seem to be a lot of high frequency waits scenarios that involve setting
and resetting the signal mask for each wait.
The application is free to modify any region before a wait call, or it
can use keep multiple regions with different settings to avoid needing to
modify the same one for wait calls. Up to a page size of regions is mapped
by default, allowing PAGE_SIZE / 64 available regions for use.
The registered region must fit within a page. On a 4kb page size system,
that allows for 64 wait regions if a full page is used, as the size of
struct io_uring_reg_wait is 64b. The region registered must be aligned
to io_uring_reg_wait in size. It's valid to register less than 64
entries.
In network performance testing with zero-copy, this reduced the time
spent waiting on the TX side from 3.12% to 0.3% and the RX side from 4.4%
to 0.3%.
Wait regions are fixed for the lifetime of the ring - once registered,
they are persistent until the ring is torn down. The regions support
minimum wait timeout as well as the regular waits.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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