kernel/linux.git/include/uapi/linux/io_uring.h, branch v6.13.2

io_uring: remove io_uring_cqwait_reg_arg

2024-11-18T16:10:49+00:00

A separate wait argument registration API was removed, also delete leftover uapi definitions. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/143b6a53591badac23632d3e6fa3e5db4b342ee2.1731942445.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

io_uring: restore back registered wait arguments

2024-11-15T19:28:38+00:00

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 Link: https://lore.kernel.org/r/81822c1b4ffbe8ad391b4f9ad1564def0d26d990.1731689588.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

io_uring: add memory region registration

2024-11-15T16:58:34+00:00

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 Link: https://lore.kernel.org/r/0798cf3a14fad19cfc96fc9feca5f3e11481691d.1731689588.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

io_uring: introduce concept of memory regions

2024-11-15T16:58:34+00:00

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 Link: https://lore.kernel.org/r/0e6fe25818dfbaebd1bd90b870a6cac503fe1a24.1731689588.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

io_uring: temporarily disable registered waits

2024-11-15T16:58:34+00:00

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 Link: https://lore.kernel.org/r/70b1d1d218c41ba77a76d1789c8641dab0b0563e.1731689588.git.asml.silence@gmail.com Signed-off-by: Jens Axboe

io_uring/napi: add static napi tracking strategy

2024-11-06T20:55:38+00:00

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 Link: https://lore.kernel.org/r/96943de14968c35a5c599352259ad98f3c0770ba.1728828877.git.olivier@trillion01.com Signed-off-by: Jens Axboe

io_uring: add support for hybrid IOPOLL

2024-11-02T21:45:30+00:00

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 Link: https://lore.kernel.org/r/20241101091957.564220-2-xue01.he@samsung.com Signed-off-by: Jens Axboe

io_uring/rsrc: allow cloning with node replacements

2024-11-02T21:45:30+00:00

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

io_uring/rsrc: allow cloning at an offset

2024-11-02T21:45:30+00:00

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

io_uring/nop: add support for testing registered files and buffers

2024-10-29T19:43:28+00:00

Useful for testing performance/efficiency impact of registered files and buffers, vs (particularly) non-registered files. Signed-off-by: Jens Axboe