Batching task work up is an important performance optimisation, as
task_work_add is expensive.
In order to keep the semantics replace the task_list with a fake node
while processing the old list, and then do a cmpxchg at the end to see if
there is more work.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220622134028.2013417-6-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With networking use cases we see contention on the spinlock used to
protect the task_list when multiple threads try and add completions at once.
Instead we can use a lockless list, and assume that the first caller to
add to the list is responsible for kicking off task work.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220622134028.2013417-4-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This optimisation has some built in assumptions that make it easy to
introduce bugs. It also does not have clear wins that make it worth keeping.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220622134028.2013417-2-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Since SQPOLL now uses TWA_SIGNAL_NO_IPI, there won't be task work items
without TIF_NOTIFY_SIGNAL. Simplify io_run_task_work() by removing
task->task_works check. Even though looks it doesn't cause extra cache
bouncing, it's still nice to not touch it an extra time when it might be
not cached.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/75d4f34b0c671075892821a409e28da6cb1d64fe.1655802465.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
task_work bits of io_uring_task are split into two cache lines causing
extra cache bouncing, place them into a separate cache line. Also move
the most used submission path fields closer together, so there are hot.
Cc: stable@vger.kernel.org # 5.15+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_poll_remove() expects poll_find() to search only for poll requests and
passes a flag for this. Just be a little bit extra cautious considering
lots of recent poll/cancellation changes and add a WARN_ON_ONCE checking
that we don't get an apoll'ed request.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ec9a66f1e22f99dcd02288d4e42f3cc6bb357804.1655684496.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
spin_lock(&ctx->completion_lock);
/* post CQEs */
io_commit_cqring(ctx);
spin_unlock(&ctx->completion_lock);
io_cqring_ev_posted(ctx);
We have many places repeating this sequence, and the three function
unlock section is not perfect from the maintainance perspective and also
makes it harder to add new locking/sync trick.
Introduce two helpers. io_cq_lock(), which is simple and only grabs
->completion_lock, and io_cq_unlock_post() encapsulating the three call
section.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/fe0c682bf7f7b55d9be55b0d034be9c1949277dc.1655684496.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Some io_uring-eventfd users assume that there won't be spurious wakeups.
That assumption has to be honoured by all io_cqring_ev_posted() callers,
which is inconvenient and from time to time leads to problems but should
be maintained to not break the userspace.
Instead of making the callers track whether a CQE was posted or not, hide
it inside io_eventfd_signal(). It saves ->cached_cq_tail it saw last time
and triggers the eventfd only when ->cached_cq_tail changed since then.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0ffc66bae37a2513080b601e4370e147faaa72c5.1655684496.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
clang complains on bitwise operations with bools, add a bit more
verbosity to better show that we want to call io_poll_remove_all_table()
twice but with different arguments.
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f11d21dcdf9233e0eeb15fa13b858a05a78eb310.1655684496.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring_try_cancel_requests() loops until there is nothing left to do
with the ring, however there might be several rings and they might have
dependencies between them, e.g. via poll requests.
Instead of cancelling rings one by one, try to cancel them all and only
then loop over if we still potenially some work to do.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8d491fe02d8ac4c77ff38061cf86b9a827e8845c.1655684496.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's not clear how widely used IOSQE_CQE_SKIP_SUCCESS is, and how often
->flush_cqes flag prevents from completion being flushed. Sometimes it's
high level of concurrency that enables it at least for one CQE, but
sometimes it doesn't save much because nobody waiting on the CQ.
Remove ->flush_cqes flag and the optimisation, it should benefit the
normal use case. Note, that there is no spurious eventfd problem with
that as checks for spuriousness were incorporated into
io_eventfd_signal().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/692e81eeddccc096f449a7960365fa7b4a18f8e6.1655637157.git.asml.silence@gmail.com
[axboe: remove now dead state->flush_cqes variable]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit 3a3d47fa9cfd ("io_uring: make io_uring_types.h public") moved
a bunch of io_uring types to a kernel wide header, so we could make
tracing a bit saner rather than pass in a ton of arguments.
However, there are a few types in there that are not really needed to
be system wide. Move the cancel data and mapped buffers back to the
appropriate io_uring local headers.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We have lots of trace events accepting an io_uring request and wanting
to print some of its fields like user_data, opcode, flags and so on.
However, as trace points were unaware of io_uring structures, we had to
pass all the fields as arguments. Teach trace/events/io_uring.h about
struct io_kiocb and stop the misery of passing a horde of arguments to
trace helpers.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/40ff72f92798114e56d400f2b003beb6cde6ef53.1655384063.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
__io_fill_cqe_req() is hot and inlined, we want it to be as small as
possible. Add io_req_cqe_overflow() accepting only a request and doing
all overflow accounting, and replace with it two calls to 6 argument
io_cqring_event_overflow().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/048b9fbcce56814d77a1a540409c98c3d383edcb.1655455613.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add comments to explain why it is always under uring lock when
incrementing head in __io_kbuf_recycle. And rectify one comemnt about
kbuf consuming in iowq case.
Signed-off-by: Hao Xu <howeyxu@tencent.com>
Link: https://lore.kernel.org/r/20220617050429.94293-1-hao.xu@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently we do two extra spin lock/unlock pairs to add a poll/apoll
request to the cancellation hash table and remove it from there.
On the submission side we often already hold ->uring_lock and tw
completion is likely to hold it as well. Add a second cancellation hash
table protected by ->uring_lock. In concerns for latency because of a
need to have the mutex locked on the completion side, use the new table
only in following cases:
1) IORING_SETUP_SINGLE_ISSUER: only one task grabs uring_lock, so there
is little to no contention and so the main tw hander will almost
always end up grabbing it before calling callbacks.
2) IORING_SETUP_SQPOLL: same as with single issuer, only one task is
a major user of ->uring_lock.
3) apoll: we normally grab the lock on the completion side anyway to
execute the request, so it's free.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1bbad9c78c454b7b92f100bbf46730a37df7194f.1655371007.git.asml.silence@gmail.com
Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new IORING_SETUP_SINGLE_ISSUER flag and the userspace visible part
of it, i.e. put limitations of submitters. Also, don't allow it together
with IOPOLL as we're not going to put it to good use.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4bcc41ee467fdf04c8aab8baf6ce3ba21858c3d4.1655371007.git.asml.silence@gmail.com
Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Don't allocate to many hash/cancellation buckets, there might be too
many, clamp it to 8 bits, or 256 * 64B = 16KB. We don't usually have too
many requests, and 256 buckets should be enough, especially since we
do hash search only in the cancellation path.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b9620c8072ba61a2d50eba894b89bd93a94a9abd.1655371007.git.asml.silence@gmail.com
Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Instead of using implicit knowledge of what is locked or not after
io_poll_find() and co returns, pass back a pointer to the locked
bucket if any. If set the user must to unlock the spinlock.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/dae1dc5749aa34367812ecf62f82fd3f053aae44.1655371007.git.asml.silence@gmail.com
Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new io_hash_bucket structure so that each bucket in cancel_hash
has separate spinlock. Use per entry lock for cancel_hash, this removes
some completion lock invocation and remove contension between different
cancel_hash entries.
Signed-off-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/05d1e135b0c8bce9d1441e6346776589e5783e26.1655371007.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
REQ_F_COMPLETE_INLINE is only needed to delay queueing into the
completion list to io_queue_sqe() as __io_req_complete() is inlined and
we don't want to bloat the kernel.
As now we complete in a more centralised fashion in io_issue_sqe() we
can get rid of the flag and queue to the list directly.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/600ba20a9338b8a39b249b23d3d177803613dde4.1655371007.git.asml.silence@gmail.com
Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_issue_sqe() from the io_uring core knows how to complete requests
based on the returned error code, we can delegate io_read()/io_write()
completion to it. Make kiocb_done() to return the right completion
code and propagate it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/32ef005b45d23bf6b5e6837740dc0331bb051bd4.1655371007.git.asml.silence@gmail.com
Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Luckily, nnobody completes multi-apoll requests outside the polling
functions, but don't set IO_URING_F_COMPLETE_DEFER in any case as
there is nobody who is catching REQ_F_COMPLETE_INLINE, and so will leak
requests if used.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a65ed3f5effd9321ee06e6edea294a03be3e15a0.1655310733.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Following timeout fields access patterns, move all of them into a
separate cache line inside ctx, so they don't intervene with normal
completion caching, especially since timeout removals and completion
are separated and the later is done via tw.
It also sheds some bytes from io_ring_ctx, 1216B -> 1152B
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4b163793072840de53b3cb66e0c2995e7226ff78.1655310733.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
As far as we know, nobody ever adopted the epoll_ctl management via
io_uring. Deprecate it now with a warning, and plan on removing it in
a later kernel version. When we do remove it, we can revert the following
commits as well:
39220e8d4a ("eventpoll: support non-blocking do_epoll_ctl() calls")
58e41a44c4 ("eventpoll: abstract out epoll_ctl() handler")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/io-uring/CAHk-=wiTyisXBgKnVHAGYCNvkmjk=50agS2Uk6nr+n3ssLZg2w@mail.gmail.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
By default, the POLL_ADD command does edge triggered poll - if we get
a non-zero mask on the initial poll attempt, we complete the request
successfully.
Support level triggered by always waiting for a notification, regardless
of whether or not the initial mask matches the file state.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We already have the declarations in opdef.h, move the rest into its own
file rather than in the main io_uring.c file.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This also helps cleanup the io_uring.h cancel parts, as we can make
things static in the cancel.c file, mostly.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a io_poll_issue() rather than export the general task_work locking
and io_issue_sqe(), and put the io_op_defs definition and structure into
a separate header file so that poll can use it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove some dead headers we no longer need, and get rid of the
io_ring_ctx and io_uring_fops forward declarations.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This also means moving a bit more of the fixed file handling to the
filetable side, which makes sense separately too.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Would be nice to sort out Kconfig for this and don't even compile
epoll.c if we don't have epoll configured.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Normally request handlers complete requests themselves, if they don't
return an error. For the latter case, the core will complete it for
them.
This is unhandy for pushing opcode handlers further out, as we don't
want a bunch of inline completion code and we don't want to make the
completion path slower than it is now.
Let the core handle any completion, unless the handler explicitly
asks us not to.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This can move request type specific cleanup into a private handler,
removing the need for the core io_uring parts to know what types
they are dealing with.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There's a special case for recvmsg with MSG_ERRQUEUE set. This is
problematic as it means the core needs to know about this special
request type.
For now, just add a generic flag for it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove struct io_poll_update from io_kiocb, and convert the poll path to
use the io_cmd_type approach instead.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove struct io_poll_iocb from io_kiocb, and convert the poll path to
use the io_cmd_type approach instead.
While at it, rename io_poll_iocb to io_poll which is consistent with the
other request type private structures.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove struct io_rw from io_kiocb, and convert the read/write path to
use the io_cmd_type approach instead.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Each opcode generally has a command structure in io_kiocb which it can
use to store data associated with that request.
In preparation for having the core layer not know about what's inside
these fields, add a generic io_cmd_data type and put in the union as
well.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Define an io_op_def->prep_async() handler and push the async preparation
to there. Since we now have that, we can drop ->needs_async_setup, as
they mean the same thing.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In preparation for splitting io_uring up a bit, move it into its own
top level directory. It didn't really belong in fs/ anyway, as it's
not a file system only API.
This adds io_uring/ and moves the core files in there, and updates the
MAINTAINERS file for the new location.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
