Commit Graph

1074215 Commits

Author SHA1 Message Date
Jens Axboe
abdad709ed io_uring: recycle provided before arming poll
We currently have a race where we recycle the selected buffer if poll
returns IO_APOLL_OK. But that's too late, as the poll could already be
triggering or have triggered. If that race happens, then we're putting a
buffer that's already being used.

Fix this by recycling before we arm poll. This does mean that we'll
sometimes almost instantly re-select the buffer, but it's rare enough in
testing that it should not pose a performance issue.

Fixes: b1c6264575 ("io_uring: recycle provided buffers if request goes async")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-20 07:23:57 -06:00
Jens Axboe
5e92936746 io_uring: terminate manual loop iterator loop correctly for non-vecs
The fix for not advancing the iterator if we're using fixed buffers is
broken in that it can hit a condition where we don't terminate the loop.
This results in io-wq looping forever, asking to read (or write) 0 bytes
for every subsequent loop.

Reported-by: Joel Jaeschke <joel.jaeschke@gmail.com>
Link: https://github.com/axboe/liburing/issues/549
Fixes: 16c8d2df7e ("io_uring: ensure symmetry in handling iter types in loop_rw_iter()")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-18 11:42:48 -06:00
Jens Axboe
adf3a9e9f5 io_uring: don't check unrelated req->open.how in accept request
Looks like a victim of too much copy/paste, we should not be looking
at req->open.how in accept. The point is to check CLOEXEC and error
out, which we don't invalid direct descriptors on exec. Hence any
attempt to get a direct descriptor with CLOEXEC is invalid.

No harm is done here, as req->open.how.flags overlaps with
req->accept.flags, but it's very confusing and might change if either of
those command structs are modified.

Fixes: aaa4db12ef ("io_uring: accept directly into fixed file table")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-18 10:57:19 -06:00
Jens Axboe
dbc7d452e7 io_uring: manage provided buffers strictly ordered
Workloads using provided buffers benefit from using and returning buffers
in the right order, and so does TLBs for that matter. Manage the internal
buffer list in a straight list, rather than use the head buffer as the
insertion node. Use a hashed list for the buffer group IDs instead of
xarray, the overhead is much lower this way. xarray provides internal
locking and other trickery that is handy for some uses cases, but
io_uring already locks internally for the buffer manipulation and needs
none of that.

This is good for about a 2% reduction in overhead, combination of the
improved management and the fact that the workload has an easier time
bundling back provided buffers.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-17 17:20:10 -06:00
Pavel Begunkov
9aa8dfde48 io_uring: fold evfd signalling under a slower path
Add ->has_evfd flag, which is true IFF there is an eventfd attached, and
use it to hide io_eventfd_signal() into __io_commit_cqring_flush() and
combine fast checks in a single if. Also, gcc 11.2 wasn't inlining
io_cqring_ev_posted() without this change, so helps with that as well.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f6168471997decded475a063f92915787975a30b.1647481208.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 20:26:32 -06:00
Pavel Begunkov
9333f6b462 io_uring: thin down io_commit_cqring()
io_commit_cqring() is currently always under spinlock section, so it's
always better to keep it as slim as possible. Move
__io_commit_cqring_flush() out of it into ev_posted*(). If fast checks
do fail and this post-processing is required, we'll reacquire
->completion_lock, which is fine as we don't care about performance of
draining and offset timeouts.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ec4e81fd720d3bc7bca8cb9152e080dad1a052f1.1647481208.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 20:26:32 -06:00
Pavel Begunkov
66fc25ca6b io_uring: shuffle io_eventfd_signal() bits around
A preparation patch, which moves a fast ->io_ev_fd check out of
io_eventfd_signal() into ev_posted*(). Compilers are smart enough for it
to not change anything, but will need it later.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ec4091ac76d43912b73917e8db651c2dac4b7b01.1647481208.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 20:26:32 -06:00
Pavel Begunkov
0f84747177 io_uring: remove extra barrier for non-sqpoll iopoll
smp_mb() in io_cqring_ev_posted_iopoll() is only there because of
waitqueue_active(). However, non-SQPOLL IOPOLL ring doesn't wake the CQ
and so the barrier there is useless. Kill it, it's usually pretty
expensive.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d72e8ef6f7a3f6a72e18fad8409f7d47afc8da7d.1647481208.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 20:26:32 -06:00
Pavel Begunkov
b91ef18728 io_uring: fix provided buffer return on failure for kiocb_done()
Use io_req_complete_failed() in kiocb_done(). This cleans up the code,
but also ensures that a provided buffers is correctly freed on failure.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a4880106fcf199d5810707fe2d17126fcdf18bc4.1647481208.git.asml.silence@gmail.com
[axboe: split from previous patch]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 20:24:47 -06:00
Pavel Begunkov
3b2b78a8eb io_uring: extend provided buf return to fails
It's never a good idea to put provided buffers without notifying the
userspace, it'll lead to userspace leaks, so add io_put_kbuf() in
io_req_complete_failed(). The fail helper is called by all sorts of
requests, but it's still safe to do as io_put_kbuf() will return 0 in
for all requests that don't support and so don't expect provided buffers.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a4880106fcf199d5810707fe2d17126fcdf18bc4.1647481208.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 20:24:28 -06:00
Pavel Begunkov
6695490dc8 io_uring: refactor timeout cancellation cqe posting
io_fill_cqe*() is not always the best way to post CQEs just because
there is enough of infrastructure on top. Replace a raw call to a
variant of it inside of io_timeout_cancel(), which also saves us some
bloating and might help with batching later.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/46113ec4345764b4aef3b384ce38cceabaeedcbb.1647481208.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 20:11:15 -06:00
Pavel Begunkov
ae4da18941 io_uring: normilise naming for fill_cqe*
Restore consistency in __io_fill_cqe* like helpers, always honouring
"io_" prefix and adding "req" when we're passing in a request.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/bd016ff5c1a4f74687828069d2619d8a65e0c6d7.1647481208.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 20:11:00 -06:00
Jens Axboe
91eac1c69c io_uring: cache poll/double-poll state with a request flag
With commit "io_uring: cache req->apoll->events in req->cflags" applied,
we now have just io_poll_remove_entries() dipping into req->apoll when
it isn't strictly necessary.

Mark poll and double-poll with a flag, so we know if we need to look
at apoll->double_poll. This avoids pulling in those cachelines if we
don't need them. The common case is that the poll wake handler already
removed these entries while hot off the completion path.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 16:59:10 -06:00
Jens Axboe
81459350d5 io_uring: cache req->apoll->events in req->cflags
When we arm poll on behalf of a different type of request, like a network
receive, then we allocate req->apoll as our poll entry. Running network
workloads shows io_poll_check_events() as the most expensive part of
io_uring, and it's all due to having to pull in req->apoll instead of
just the request which we have hot already.

Cache poll->events in req->cflags, which isn't used until the request
completes anyway. This isn't strictly needed for regular poll, where
req->poll.events is used and thus already hot, but for the sake of
unification we do it all around.

This saves 3-4% of overhead in certain request workloads.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 16:55:05 -06:00
Jens Axboe
521d61fc76 io_uring: move req->poll_refs into previous struct hole
This serves two purposes:

- We now have the last cacheline mostly unused for generic workloads,
  instead of having to pull in the poll refs explicitly for workloads
  that rely on poll arming.

- It shrinks the io_kiocb from 232 to 224 bytes.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 12:53:23 -06:00
Dylan Yudaken
052ebf1fbb io_uring: make tracing format consistent
Make the tracing formatting for user_data and flags consistent.

Having consistent formatting allows one for example to grep for a specific
user_data/flags and be able to trace a single sqe through easily.

Change user_data to 0x%llx and flags to 0x%x everywhere. The '0x' is
useful to disambiguate for example "user_data 100".

Additionally remove the '=' for flags in io_uring_req_failed, again for consistency.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220316095204.2191498-1-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-16 05:45:28 -06:00
Jens Axboe
4d9237e32c io_uring: recycle apoll_poll entries
Particularly for networked workloads, io_uring intensively uses its
poll based backend to get a notification when data/space is available.
Profiling workloads, we see 3-4% of alloc+free that is directly attributed
to just the apoll allocation and free (and the rest being skb alloc+free).

For the fast path, we have ctx->uring_lock held already for both issue
and the inline completions, and we can utilize that to avoid any extra
locking needed to have a basic recycling cache for the apoll entries on
both the alloc and free side.

Double poll still requires an allocation. But those are rare and not
a fast path item.

With the simple cache in place, we see a 3-4% reduction in overhead for
the workload.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-15 10:54:08 -06:00
Jens Axboe
f3b6a41eb2 io_uring: remove duplicated member check for io_msg_ring_prep()
Julia and the kernel test robot report that the prep handling for this
command inadvertently checks one field twice:

fs/io_uring.c:4338:42-56: duplicated argument to && or ||

Get rid of it.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Fixes: 4f57f06ce2 ("io_uring: add support for IORING_OP_MSG_RING command")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-12 06:50:13 -07:00
Jens Axboe
bcbb7bf6cc io_uring: allow submissions to continue on error
By default, io_uring will stop submitting a batch of requests if we run
into an error submitting a request. This isn't strictly necessary, as
the error result is passed out-of-band via a CQE anyway. And it can be
a bit confusing for some applications.

Provide a way to setup a ring that will continue submitting on error,
when the error CQE has been posted.

There's still one case that will break out of submission. If we fail
allocating a request, then we'll still return -ENOMEM. We could in theory
post a CQE for that condition too even if we never got a request. Leave
that for a potential followup.

Reported-by: Dylan Yudaken <dylany@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 13:05:25 -07:00
Jens Axboe
b1c6264575 io_uring: recycle provided buffers if request goes async
If we are using provided buffers, it's less than useful to have a buffer
selected and pinned if a request needs to go async or arms poll for
notification trigger on when we can process it.

Recycle the buffer in those events, so we don't pin it for the duration
of the request.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 09:55:01 -07:00
Jens Axboe
2be2eb02e2 io_uring: ensure reads re-import for selected buffers
If we drop buffers between scheduling a retry, then we need to re-import
when we start the request again.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 09:55:01 -07:00
Jens Axboe
9af177ee3e io_uring: retry early for reads if we can poll
Most of the logic in io_read() deals with regular files, and in some ways
it would make sense to split the handling into S_IFREG and others. But
at least for retry, we don't need to bother setting up a bunch of state
just to abort in the loop later. In particular, don't bother forcing
setup of async data for a normal non-vectored read when we don't need it.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 09:45:57 -07:00
Olivier Langlois
adc8682ec6 io_uring: Add support for napi_busy_poll
The sqpoll thread can be used for performing the napi busy poll in a
similar way that it does io polling for file systems supporting direct
access bypassing the page cache.

The other way that io_uring can be used for napi busy poll is by
calling io_uring_enter() to get events.

If the user specify a timeout value, it is distributed between polling
and sleeping by using the systemwide setting
/proc/sys/net/core/busy_poll.

The changes have been tested with this program:
https://github.com/lano1106/io_uring_udp_ping

and the result is:
Without sqpoll:
NAPI busy loop disabled:
rtt min/avg/max/mdev = 40.631/42.050/58.667/1.547 us
NAPI busy loop enabled:
rtt min/avg/max/mdev = 30.619/31.753/61.433/1.456 us

With sqpoll:
NAPI busy loop disabled:
rtt min/avg/max/mdev = 42.087/44.438/59.508/1.533 us
NAPI busy loop enabled:
rtt min/avg/max/mdev = 35.779/37.347/52.201/0.924 us

Co-developed-by: Hao Xu <haoxu@linux.alibaba.com>
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Link: https://lore.kernel.org/r/810bd9408ffc510ff08269e78dca9df4af0b9e4e.1646777484.git.olivier@trillion01.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 09:18:30 -07:00
Olivier Langlois
950e79dd73 io_uring: minor io_cqring_wait() optimization
Move up the block manipulating the sig variable to execute code
that may encounter an error and exit first before continuing
executing the rest of the function and avoid useless computations

Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Link: https://lore.kernel.org/r/84513f7cc1b1fb31d8f4cb910aee033391d036b4.1646777484.git.olivier@trillion01.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 09:18:30 -07:00
Jens Axboe
4f57f06ce2 io_uring: add support for IORING_OP_MSG_RING command
This adds support for IORING_OP_MSG_RING, which allows an SQE to signal
another ring. That allows either waking up someone waiting on the ring,
or even passing a 64-bit value via the user_data field in the CQE.

sqe->fd must contain the fd of a ring that should receive the CQE.
sqe->off will be propagated to the cqe->user_data on the target ring,
and sqe->len will be propagated to cqe->res. The results CQE will have
IORING_CQE_F_MSG set in its flags, to indicate that this CQE was generated
from a messaging request rather than a SQE issued locally on that ring.
This effectively allows passing a 64-bit and a 32-bit quantify between
the two rings.

This request type has the following request specific error cases:

- -EBADFD. Set if the sqe->fd doesn't point to a file descriptor that is
  of the io_uring type.
- -EOVERFLOW. Set if we were not able to deliver a request to the target
  ring.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 09:16:04 -07:00
Jens Axboe
cc3cec8367 io_uring: speedup provided buffer handling
In testing high frequency workloads with provided buffers, we spend a
lot of time in allocating and freeing the buffer units themselves.
Rather than repeatedly free and alloc them, add a recycling cache
instead. There are two caches:

- ctx->io_buffers_cache. This is the one we grab from in the submission
  path, and it's protected by ctx->uring_lock. For inline completions,
  we can recycle straight back to this cache and not need any extra
  locking.

- ctx->io_buffers_comp. If we're not under uring_lock, then we use this
  list to recycle buffers. It's protected by the completion_lock.

On adding a new buffer, check io_buffers_cache. If it's empty, check if
we can splice entries from the io_buffers_comp_cache.

This reduces about 5-10% of overhead from provided buffers, bringing it
pretty close to the non-provided path.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:33:14 -07:00
Jens Axboe
e7a6c00dc7 io_uring: add support for registering ring file descriptors
Lots of workloads use multiple threads, in which case the file table is
shared between them. This makes getting and putting the ring file
descriptor for each io_uring_enter(2) system call more expensive, as it
involves an atomic get and put for each call.

Similarly to how we allow registering normal file descriptors to avoid
this overhead, add support for an io_uring_register(2) API that allows
to register the ring fds themselves:

1) IORING_REGISTER_RING_FDS - takes an array of io_uring_rsrc_update
   structs, and registers them with the task.
2) IORING_UNREGISTER_RING_FDS - takes an array of io_uring_src_update
   structs, and unregisters them.

When a ring fd is registered, it is internally represented by an offset.
This offset is returned to the application, and the application then
uses this offset and sets IORING_ENTER_REGISTERED_RING for the
io_uring_enter(2) system call. This works just like using a registered
file descriptor, rather than a real one, in an SQE, where
IOSQE_FIXED_FILE gets set to tell io_uring that we're using an internal
offset/descriptor rather than a real file descriptor.

In initial testing, this provides a nice bump in performance for
threaded applications in real world cases where the batch count (eg
number of requests submitted per io_uring_enter(2) invocation) is low.
In a microbenchmark, submitting NOP requests, we see the following
increases in performance:

Requests per syscall	Baseline	Registered	Increase
----------------------------------------------------------------
1			 ~7030K		 ~8080K		+15%
2			~13120K		~14800K		+13%
4			~22740K		~25300K		+11%

Co-developed-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Dylan Yudaken
63c3654973 io_uring: documentation fixup
Fix incorrect name reference in comment. ki_filp does not exist in the
struct, but file does.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220224105157.1332353-1-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Dylan Yudaken
b4aec40015 io_uring: do not recalculate ppos unnecessarily
There is a slight optimisation to be had by calculating the correct pos
pointer inside io_kiocb_update_pos and then using that later.

It seems code size drops by a bit:
000000000000a1b0 0000000000000400 t io_read
000000000000a5b0 0000000000000319 t io_write

vs
000000000000a1b0 00000000000003f6 t io_read
000000000000a5b0 0000000000000310 t io_write

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Dylan Yudaken
d34e1e5b39 io_uring: update kiocb->ki_pos at execution time
Update kiocb->ki_pos at execution time rather than in io_prep_rw().
io_prep_rw() happens before the job is enqueued to a worker and so the
offset might be read multiple times before being executed once.

Ensures that the file position in a set of _linked_ SQEs will be only
obtained after earlier SQEs have completed, and so will include their
incremented file position.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Dylan Yudaken
af9c45eceb io_uring: remove duplicated calls to io_kiocb_ppos
io_kiocb_ppos is called in both branches, and it seems that the compiler
does not fuse this. Fusing removes a few bytes from loop_rw_iter.

Before:
$ nm -S fs/io_uring.o | grep loop_rw_iter
0000000000002430 0000000000000124 t loop_rw_iter

After:
$ nm -S fs/io_uring.o | grep loop_rw_iter
0000000000002430 000000000000010d t loop_rw_iter

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Olivier Langlois
c5020bc8d9 io_uring: Remove unneeded test in io_run_task_work_sig()
Avoid testing TIF_NOTIFY_SIGNAL twice by calling task_sigpending()
directly from io_run_task_work_sig()

Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Link: https://lore.kernel.org/r/bd7c0495f7656e803e5736708591bb665e6eaacd.1645041650.git.olivier@trillion01.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Stefan Roesch
502c87d655 io-uring: Make tracepoints consistent.
This makes the io-uring tracepoints consistent. Where it makes sense
the tracepoints start with the following four fields:
- context (ring)
- request
- user_data
- opcode.

Signed-off-by: Stefan Roesch <shr@fb.com>
Link: https://lore.kernel.org/r/20220214180430.70572-3-shr@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Stefan Roesch
d5ec1dfaf5 io-uring: add __fill_cqe function
This introduces the __fill_cqe function. This is necessary
to correctly issue the io_uring_complete tracepoint.

Signed-off-by: Stefan Roesch <shr@fb.com>
Link: https://lore.kernel.org/r/20220214180430.70572-2-shr@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Hao Xu
86127bb18a io-wq: use IO_WQ_ACCT_NR rather than hardcoded number
It's better to use the defined enum stuff not the hardcoded number to
define array.

Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220206095241.121485-4-haoxu@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Hao Xu
e13fb1fe14 io-wq: reduce acct->lock crossing functions lock/unlock
reduce acct->lock lock and unlock in different functions to make the
code clearer.

Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220206095241.121485-3-haoxu@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Hao Xu
42abc95f05 io-wq: decouple work_list protection from the big wqe->lock
wqe->lock is abused, it now protects acct->work_list, hash stuff,
nr_workers, wqe->free_list and so on. Lets first get the work_list out
of the wqe-lock mess by introduce a specific lock for work list. This
is the first step to solve the huge contension between work insertion
and work consumption.
good thing:
  - split locking for bound and unbound work list
  - reduce contension between work_list visit and (worker's)free_list.

For the hash stuff, since there won't be a work with same file in both
bound and unbound work list, thus they won't visit same hash entry. it
works well to use the new lock to protect hash stuff.

Results:
set max_unbound_worker = 4, test with echo-server:
nice -n -15 ./io_uring_echo_server -p 8081 -f -n 1000 -l 16
(-n connection, -l workload)
before this patch:
Samples: 2M of event 'cycles:ppp', Event count (approx.): 1239982111074
Overhead  Command          Shared Object         Symbol
  28.59%  iou-wrk-10021    [kernel.vmlinux]      [k] native_queued_spin_lock_slowpath
   8.89%  io_uring_echo_s  [kernel.vmlinux]      [k] native_queued_spin_lock_slowpath
   6.20%  iou-wrk-10021    [kernel.vmlinux]      [k] _raw_spin_lock
   2.45%  io_uring_echo_s  [kernel.vmlinux]      [k] io_prep_async_work
   2.36%  iou-wrk-10021    [kernel.vmlinux]      [k] _raw_spin_lock_irqsave
   2.29%  iou-wrk-10021    [kernel.vmlinux]      [k] io_worker_handle_work
   1.29%  io_uring_echo_s  [kernel.vmlinux]      [k] io_wqe_enqueue
   1.06%  iou-wrk-10021    [kernel.vmlinux]      [k] io_wqe_worker
   1.06%  io_uring_echo_s  [kernel.vmlinux]      [k] _raw_spin_lock
   1.03%  iou-wrk-10021    [kernel.vmlinux]      [k] __schedule
   0.99%  iou-wrk-10021    [kernel.vmlinux]      [k] tcp_sendmsg_locked

with this patch:
Samples: 1M of event 'cycles:ppp', Event count (approx.): 708446691943
Overhead  Command          Shared Object         Symbol
  16.86%  iou-wrk-10893    [kernel.vmlinux]      [k] native_queued_spin_lock_slowpat
   9.10%  iou-wrk-10893    [kernel.vmlinux]      [k] _raw_spin_lock
   4.53%  io_uring_echo_s  [kernel.vmlinux]      [k] native_queued_spin_lock_slowpat
   2.87%  iou-wrk-10893    [kernel.vmlinux]      [k] io_worker_handle_work
   2.57%  iou-wrk-10893    [kernel.vmlinux]      [k] _raw_spin_lock_irqsave
   2.56%  io_uring_echo_s  [kernel.vmlinux]      [k] io_prep_async_work
   1.82%  io_uring_echo_s  [kernel.vmlinux]      [k] _raw_spin_lock
   1.33%  iou-wrk-10893    [kernel.vmlinux]      [k] io_wqe_worker
   1.26%  io_uring_echo_s  [kernel.vmlinux]      [k] try_to_wake_up

spin_lock failure from 25.59% + 8.89% =  34.48% to 16.86% + 4.53% = 21.39%
TPS is similar, while cpu usage is from almost 400% to 350%

Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220206095241.121485-2-haoxu@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Nathan Chancellor
f0a4e62bb5 io_uring: Fix use of uninitialized ret in io_eventfd_register()
Clang warns:

  fs/io_uring.c:9396:9: warning: variable 'ret' is uninitialized when used here [-Wuninitialized]
          return ret;
                 ^~~
  fs/io_uring.c:9373:13: note: initialize the variable 'ret' to silence this warning
          int fd, ret;
                     ^
                      = 0
  1 warning generated.

Just return 0 directly and reduce the scope of ret to the if statement,
as that is the only place that it is used, which is how the function was
before the fixes commit.

Fixes: 1a75fac9a0f9 ("io_uring: avoid ring quiesce while registering/unregistering eventfd")
Link: https://github.com/ClangBuiltLinux/linux/issues/1579
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20220207162410.1013466-1-nathan@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Usama Arif
8bb649ee1d io_uring: remove ring quiesce for io_uring_register
None of the opcodes in io_uring_register use ring quiesce anymore. Hence
io_register_op_must_quiesce always returns false and io_ctx_quiesce is
never called.

Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Link: https://lore.kernel.org/r/20220204145117.1186568-6-usama.arif@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Usama Arif
ff16cfcfda io_uring: avoid ring quiesce while registering restrictions and enabling rings
IORING_SETUP_R_DISABLED prevents submitting requests and so there will be
no requests until IORING_REGISTER_ENABLE_RINGS is called. And
IORING_REGISTER_RESTRICTIONS works only before
IORING_REGISTER_ENABLE_RINGS is called. Hence ring quiesce is not needed
for these opcodes.

Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Link: https://lore.kernel.org/r/20220204145117.1186568-5-usama.arif@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Usama Arif
c75312dd59 io_uring: avoid ring quiesce while registering async eventfd
This is done using the RCU data structure (io_ev_fd). eventfd_async is
moved from io_ring_ctx to io_ev_fd which is RCU protected hence avoiding
ring quiesce which is much more expensive than an RCU lock. The place
where eventfd_async is read is already under rcu_read_lock so there is no
extra RCU read-side critical section needed.

Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Link: https://lore.kernel.org/r/20220204145117.1186568-4-usama.arif@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Usama Arif
77bc59b498 io_uring: avoid ring quiesce while registering/unregistering eventfd
This is done by creating a new RCU data structure (io_ev_fd) as part of
io_ring_ctx that holds the eventfd_ctx.

The function io_eventfd_signal is executed under rcu_read_lock with a
single rcu_dereference to io_ev_fd so that if another thread unregisters
the eventfd while io_eventfd_signal is still being executed, the
eventfd_signal for which io_eventfd_signal was called completes
successfully.

The process of registering/unregistering eventfd is already done under
uring_lock so multiple threads won't enter a race condition while
registering/unregistering eventfd.

With the above approach ring quiesce can be avoided which is much more
expensive then using RCU lock. On the system tested, io_uring_register
with IORING_REGISTER_EVENTFD takes less than 1ms with RCU lock, compared
to 15ms before with ring quiesce.

Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Link: https://lore.kernel.org/r/20220204145117.1186568-3-usama.arif@bytedance.com
[axboe: long line fixups]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Usama Arif
2757be22c0 io_uring: remove trace for eventfd
The information on whether eventfd is registered is not very useful and
would result in the tracepoint being enclosed in an rcu_readlock in a
later patch that tries to avoid ring quiesce for registering eventfd.

Suggested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Link: https://lore.kernel.org/r/20220204145117.1186568-2-usama.arif@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-10 06:32:49 -07:00
Linus Torvalds
ffb217a13a Linux 5.17-rc7 2022-03-06 14:28:31 -08:00
Linus Torvalds
3ee65c0f07 for-5.17-rc6-tag
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Merge tag 'for-5.17-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "A few more fixes for various problems that have user visible effects
  or seem to be urgent:

   - fix corruption when combining DIO and non-blocking io_uring over
     multiple extents (seen on MariaDB)

   - fix relocation crash due to premature return from commit

   - fix quota deadlock between rescan and qgroup removal

   - fix item data bounds checks in tree-checker (found on a fuzzed
     image)

   - fix fsync of prealloc extents after EOF

   - add missing run of delayed items after unlink during log replay

   - don't start relocation until snapshot drop is finished

   - fix reversed condition for subpage writers locking

   - fix warning on page error"

* tag 'for-5.17-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fallback to blocking mode when doing async dio over multiple extents
  btrfs: add missing run of delayed items after unlink during log replay
  btrfs: qgroup: fix deadlock between rescan worker and remove qgroup
  btrfs: fix relocation crash due to premature return from btrfs_commit_transaction()
  btrfs: do not start relocation until in progress drops are done
  btrfs: tree-checker: use u64 for item data end to avoid overflow
  btrfs: do not WARN_ON() if we have PageError set
  btrfs: fix lost prealloc extents beyond eof after full fsync
  btrfs: subpage: fix a wrong check on subpage->writers
2022-03-06 12:19:36 -08:00
Linus Torvalds
f81664f760 x86 guest:
* Tweaks to the paravirtualization code, to avoid using them
 when they're pointless or harmful
 
 x86 host:
 
 * Fix for SRCU lockdep splat
 
 * Brown paper bag fix for the propagation of errno
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "x86 guest:

   - Tweaks to the paravirtualization code, to avoid using them when
     they're pointless or harmful

  x86 host:

   - Fix for SRCU lockdep splat

   - Brown paper bag fix for the propagation of errno"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: pull kvm->srcu read-side to kvm_arch_vcpu_ioctl_run
  KVM: x86/mmu: Passing up the error state of mmu_alloc_shadow_roots()
  KVM: x86: Yield to IPI target vCPU only if it is busy
  x86/kvmclock: Fix Hyper-V Isolated VM's boot issue when vCPUs > 64
  x86/kvm: Don't waste memory if kvmclock is disabled
  x86/kvm: Don't use PV TLB/yield when mwait is advertised
2022-03-06 12:08:42 -08:00
Linus Torvalds
9bdeaca18b powerpc fixes for 5.17 #5
Fix build failure when CONFIG_PPC_64S_HASH_MMU is not set.
 
 Thanks to: Murilo Opsfelder Araujo, Erhard F.
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Merge tag 'powerpc-5.17-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fix from Michael Ellerman:
 "Fix build failure when CONFIG_PPC_64S_HASH_MMU is not set.

  Thanks to Murilo Opsfelder Araujo, and Erhard F"

* tag 'powerpc-5.17-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64s: Fix build failure when CONFIG_PPC_64S_HASH_MMU is not set
2022-03-06 11:57:42 -08:00
Linus Torvalds
f40a33f5ea Two tracing fixes:
- Fix sorting on old "cpu" value in histograms
 
  - Fix return value of __setup() boot parameter handlers.
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Merge tag 'trace-v5.17-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Fix sorting on old "cpu" value in histograms

 - Fix return value of __setup() boot parameter handlers

* tag 'trace-v5.17-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix return value of __setup handlers
  tracing/histogram: Fix sorting on old "cpu" value
2022-03-06 11:47:59 -08:00
Linus Torvalds
dcde98da99 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
Pull input updates from Dmitry Torokhov:

 - a fixup for Goodix touchscreen driver allowing it to work on certain
   Cherry Trail devices

 - a fix for imbalanced enable/disable regulator in Elam touchpad driver
   that became apparent when used with Asus TF103C 2-in-1 dock

 - a couple new input keycodes used on newer keyboards

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  HID: add mapping for KEY_ALL_APPLICATIONS
  HID: add mapping for KEY_DICTATE
  Input: elan_i2c - fix regulator enable count imbalance after suspend/resume
  Input: elan_i2c - move regulator_[en|dis]able() out of elan_[en|dis]able_power()
  Input: goodix - workaround Cherry Trail devices with a bogus ACPI Interrupt() resource
  Input: goodix - use the new soc_intel_is_byt() helper
  Input: samsung-keypad - properly state IOMEM dependency
2022-03-05 15:49:45 -08:00
Linus Torvalds
0014404f9c Merge branch 'akpm' (patches from Andrew)
Merge misc fixes from Andrew Morton:
 "8 patches.

  Subsystems affected by this patch series: mm (hugetlb, pagemap, and
  userfaultfd), memfd, selftests, and kconfig"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  configs/debug: set CONFIG_DEBUG_INFO=y properly
  proc: fix documentation and description of pagemap
  kselftest/vm: fix tests build with old libc
  memfd: fix F_SEAL_WRITE after shmem huge page allocated
  mm: fix use-after-free when anon vma name is used after vma is freed
  mm: prevent vm_area_struct::anon_name refcount saturation
  mm: refactor vm_area_struct::anon_vma_name usage code
  selftests/vm: cleanup hugetlb file after mremap test
2022-03-05 12:03:14 -08:00