user/sven/linux.git/include/linux/io_uring.h, branch v5.18.6

io_uring: add support for registering ring file descriptors

2022-03-10T13:32:49Z

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 Signed-off-by: Jens Axboe

io_uring: remove files pointer in cancellation functions

2021-08-23T19:10:37Z

When doing cancellation, we use a parameter to indicate where it's from do_exit or exec. So a boolean value is good enough for this, remove the struct files* as it is not necessary. Signed-off-by: Hao Xu [axboe: fixup io_uring_files_cancel for !CONFIG_IO_URING] Signed-off-by: Jens Axboe

io_uring: extract io_uring_files_cancel() in io_uring_task_cancel()

2021-08-23T19:10:37Z

Extract io_uring_files_cancel() call in io_uring_task_cancel() to make io_uring_files_cancel() and io_uring_task_cancel() coherent and easy to read. Signed-off-by: Hao Xu Signed-off-by: Jens Axboe

io_uring: unify files and task cancel

2021-04-12T01:30:41Z

Now __io_uring_cancel() and __io_uring_files_cancel() are very similar and mostly differ by how we count requests, merge them and allow tctx_inflight() to handle counting. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/1a5986a97df4dc1378f3fe0ca1eb483dbcf42112.1618101759.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

io_uring: remove structures from include/linux/io_uring.h

2021-03-18T15:44:35Z

Link: https://lore.kernel.org/r/8c1d14f3748105f4caeda01716d47af2fa41d11c.1615809009.git.metze@samba.org Signed-off-by: Stefan Metzmacher Signed-off-by: Jens Axboe

io_uring: index io_uring->xa by ctx not file

2021-03-07T21:12:43Z

We don't use task file notes anymore, and no need left in indexing task->io_uring->xa by file, and replace it with ctx. It's better design-wise, especially since we keep a dangling file, and so have to keep an eye on not dereferencing it. Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe

io_uring: destroy io-wq on exec

2021-03-04T13:36:22Z

Destroy current's io-wq backend and tctx on __io_uring_task_cancel(), aka exec(). Looks it's not strictly necessary, because it will be done at some point when the task dies and changes of creds/files/etc. are handled, but better to do that earlier to free io-wq and not potentially lock previous mm and other resources for the time being. It's safe to do because we wait for all requests of the current task to complete, so no request will use tctx afterwards. Note, that io_uring_files_cancel() may leave some requests for later reaping, so it leaves tctx intact, that's ok as the task is dying anyway. Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe

io_uring: ensure io-wq context is always destroyed for tasks

2021-02-24T03:33:36Z

If the task ends up doing no IO, the context list is empty and we don't call into __io_uring_files_cancel() when the task exits. This can cause a leak of the io-wq structures. Ensure we always call __io_uring_files_cancel(), even if the task context list is empty. Fixes: 5aa75ed5b93f ("io_uring: tie async worker side to the task context") Signed-off-by: Jens Axboe

io_uring: remove io_identity

2021-02-22T00:25:22Z

We are no longer grabbing state, so no need to maintain an IO identity that we COW if there are changes. Signed-off-by: Jens Axboe

io_uring: tie async worker side to the task context

2021-02-22T00:25:22Z

Move it outside of the io_ring_ctx, and tie it to the io_uring task context. Signed-off-by: Jens Axboe