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2021-06-30io_uring: code clean for kiocb_done()Hao Xu1-1/+1
A simple code clean for kiocb_done() Signed-off-by: Hao Xu <haoxu@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: spin in iopoll() only when reqs are in a single queueHao Xu1-6/+14
We currently spin in iopoll() when requests to be iopolled are for same file(device), while one device may have multiple hardware queues. given an example: hw_queue_0 | hw_queue_1 req(30us) req(10us) If we first spin on iopolling for the hw_queue_0. the avg latency would be (30us + 30us) / 2 = 30us. While if we do round robin, the avg latency would be (30us + 10us) / 2 = 20us since we reap the request in hw_queue_1 in time. So it's better to do spinning only when requests are in same hardware queue. Signed-off-by: Hao Xu <haoxu@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: pre-initialise some of req fieldsPavel Begunkov1-6/+18
Most of requests are allocated from an internal cache, so it's waste of time fully initialising them every time. Instead, let's pre-init some of the fields we can during initial allocation (e.g. kmalloc(), see io_alloc_req()) and keep them valid on request recycling. There are four of them in this patch: ->ctx is always stays the same ->link is NULL on free, it's an invariant ->result is not even needed to init, just a precaution ->async_data we now clean in io_dismantle_req() as it's likely to never be allocated. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/892ba0e71309bba9fe9e0142472330bbf9d8f05d.1624739600.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: refactor io_submit_flush_completionsPavel Begunkov1-5/+5
Don't init req_batch before we actually need it. Also, add a small clean up for req declaration. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/ad85512e12bd3a20d521e9782750300970e5afc8.1624739600.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: optimise hot path restricted checksPavel Begunkov1-2/+2
Move likely/unlikely from io_check_restriction() to specifically ctx->restricted check, because doesn't do what it supposed to and make the common path take an extra jump. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/22bf70d0a543dfc935d7276bdc73081784e30698.1624739600.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: remove not needed PF_EXITING checkPavel Begunkov1-7/+2
Since cancellation got moved before exit_signals(), there is no one left who can call io_run_task_work() with PF_EXIING set, so remove the check. Note that __io_req_task_submit() still needs a similar check. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/f7f305ececb1e6044ea649fb983ca754805bb884.1624739600.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: mainstream sqpoll task_work runningPavel Begunkov1-4/+3
task_works are widely used, so place io_run_task_work() directly into the main path of io_sq_thread(), and remove it from other places where it's not needed anymore. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/24eb5e35d519c590d3dffbd694b4c61a5fe49029.1624739600.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: refactor io_arm_poll_handler()Pavel Begunkov1-21/+16
gcc 11 goes a weird path and duplicates most of io_arm_poll_handler() for READ and WRITE cases. Help it and move all pollin vs pollout specific bits under a single if-else, so there is no temptation for this kind of unfolding. before vs after: text data bss dec hex filename 85362 12650 8 98020 17ee4 ./fs/io_uring.o 85186 12650 8 97844 17e34 ./fs/io_uring.o Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/1deea0037293a922a0358e2958384b2e42437885.1624739600.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: reduce latency by reissueing the operationOlivier Langlois1-9/+22
It is quite frequent that when an operation fails and returns EAGAIN, the data becomes available between that failure and the call to vfs_poll() done by io_arm_poll_handler(). Detecting the situation and reissuing the operation is much faster than going ahead and push the operation to the io-wq. Performance improvement testing has been performed with: Single thread, 1 TCP connection receiving a 5 Mbps stream, no sqpoll. 4 measurements have been taken: 1. The time it takes to process a read request when data is already available 2. The time it takes to process by calling twice io_issue_sqe() after vfs_poll() indicated that data was available 3. The time it takes to execute io_queue_async_work() 4. The time it takes to complete a read request asynchronously 2.25% of all the read operations did use the new path. ready data (baseline) avg 3657.94182918628 min 580 max 20098 stddev 1213.15975908162 reissue completion average 7882.67567567568 min 2316 max 28811 stddev 1982.79172973284 insert io-wq time average 8983.82276995305 min 3324 max 87816 stddev 2551.60056552038 async time completion average 24670.4758861127 min 10758 max 102612 stddev 3483.92416873804 Conclusion: On average reissuing the sqe with the patch code is 1.1uSec faster and in the worse case scenario 59uSec faster than placing the request on io-wq On average completion time by reissuing the sqe with the patch code is 16.79uSec faster and in the worse case scenario 73.8uSec faster than async completion. Signed-off-by: Olivier Langlois <olivier@trillion01.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/9e8441419bb1b8f3c3fcc607b2713efecdef2136.1624364038.git.olivier@trillion01.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: add IOPOLL and reserved field checks to IORING_OP_UNLINKATJens Axboe1-0/+4
We can't support IOPOLL with non-pollable request types, and we should check for unused/reserved fields like we do for other request types. Fixes: 14a1143b68ee ("io_uring: add support for IORING_OP_UNLINKAT") Cc: stable@vger.kernel.org Reported-by: Dmitry Kadashev <dkadashev@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: add IOPOLL and reserved field checks to IORING_OP_RENAMEATJens Axboe1-0/+4
We can't support IOPOLL with non-pollable request types, and we should check for unused/reserved fields like we do for other request types. Fixes: 80a261fd0032 ("io_uring: add support for IORING_OP_RENAMEAT") Cc: stable@vger.kernel.org Reported-by: Dmitry Kadashev <dkadashev@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: refactor io_openat2()Pavel Begunkov1-15/+14
Put do_filp_open() fail path of io_openat2() under a single if, deduplicating put_unused_fd(), making it look better and helping the hot path. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/f4c84d25c049d0af2adc19c703bbfef607200209.1624543113.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: update sqe layout build checksPavel Begunkov1-0/+2
Add missing BUILD_BUG_SQE_ELEM() for ->buf_group verifying that SQE layout doesn't change. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/1f9d21bd74599b856b3a632be4c23ffa184a3ef0.1624543113.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: fix code style problemsPavel Begunkov1-8/+8
Fix a bunch of problems mostly found by checkpatch.pl Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/cfaf9a2f27b43934144fe9422a916bd327099f44.1624543113.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: refactor io_sq_thread()Pavel Begunkov1-3/+3
Move needs_sched declaration into the block where it's used, so it's harder to misuse/wrongfully reuse. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/e4a07db1353ee38b924dd1b45394cf8e746130b4.1624543113.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-30io_uring: don't change sqpoll creds if not neededPavel Begunkov1-7/+7
SQPOLL doesn't need to change creds if it's not submitting requests. Move creds overriding into __io_sq_thread() after checking if there are SQEs pending. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/c54368da2357ac539e0a333f7cfff70d5fb045b2.1624543113.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-23io_uring: Create define to modify a SQPOLL parameterOlivier Langlois1-2/+3
The magic number used to cap the number of entries extracted from an io_uring instance SQ before moving to the other instances is an interesting parameter to experiment with. A define has been created to make it easy to change its value from a single location. Signed-off-by: Olivier Langlois <olivier@trillion01.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/b401640063e77ad3e9f921e09c9b3ac10a8bb923.1624473200.git.olivier@trillion01.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-23io_uring: Fix race condition when sqp thread goes to sleepOlivier Langlois1-1/+1
If an asynchronous completion happens before the task is preparing itself to wait and set its state to TASK_INTERRUPTIBLE, the completion will not wake up the sqp thread. Cc: stable@vger.kernel.org Signed-off-by: Olivier Langlois <olivier@trillion01.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/d1419dc32ec6a97b453bee34dc03fa6a02797142.1624473200.git.olivier@trillion01.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: improve in tctx_task_work() resubmissionPavel Begunkov1-4/+8
If task_state is cleared, io_req_task_work_add() will go the slow path adding a task_work, setting the task_state, waking up the task and so on. Not to mention it's expensive. tctx_task_work() first clears the state and then executes all the work items queued, so if any of them resubmits or adds new task_work items, it would unnecessarily go through the slow path of io_req_task_work_add(). Let's clear the ->task_state at the end. We still have to check ->task_list for emptiness afterward to synchronise with io_req_task_work_add(), do that, and set the state back if we're going to retry, because clearing not-ours task_state on the next iteration would be buggy. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/1ef72cdac7022adf0cd7ce4bfe3bb5c82a62eb93.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: don't resched with empty task_listPavel Begunkov1-1/+3
Entering tctx_task_work() with empty task_list is a strange scenario, that can happen only on rare occasion during task exit, so let's not check for task_list emptiness in advance and do it do-while style. The code still correct for the empty case, just would do extra work about which we don't care. Do extra step and do the check before cond_resched(), so we don't resched if have nothing to execute. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/c4173e288e69793d03c7d7ce826f9d28afba718a.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: refactor tctx task_work list splicingPavel Begunkov1-6/+1
We don't need a full copy of tctx->task_list in tctx_task_work(), but only a first one, so just assign node directly. Taking into account that task_works are run in a context of a task, it's very unlikely to first see non-empty tctx->task_list and then splice it empty, can only happen with task_work cancellations that is not-normal slow path anyway. Hence, get rid of the check in the end, it's there not for validity but "performance" purposes. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/d076c83fedb8253baf43acb23b8fafd7c5da1714.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: optimise task_work submit flushingPavel Begunkov1-2/+3
tctx_task_work() tries to fetch a next batch of requests, but before it would flush completions from the previous batch that may be sub-optimal. E.g. io_req_task_queue() executes a head of the link where all the linked may be enqueued through the same io_req_task_queue(). And there are more cases for that. Do the flushing at the end, so it can cache completions of several waves of a single tctx_task_work(), and do the flush at the very end. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/3cac83934e4fbce520ff8025c3524398b3ae0270.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: inline __tctx_task_work()Pavel Begunkov1-36/+31
Inline __tctx_task_work() into tctx_task_work() in preparation for further optimisations. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/f9c05c4bc9763af7bd8e25ebc3c5f7b6f69148f8.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: refactor io_get_sequence()Pavel Begunkov1-6/+5
Clean up io_get_sequence() and add a comment describing the magic around sequence correction. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/f55dc409936b8afa4698d24b8677a34d31077ccb.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: clean all flags in io_clean_op() at oncePavel Begunkov1-8/+6
Clean all flags in io_clean_op() in the end in one operation, will save us a couple of operation and binary size. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/b8efe1f022a037f74e7fe497c69fb554d59bfeaf.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: simplify iovec freeing in io_clean_op()Pavel Begunkov1-2/+2
We don't get REQ_F_NEED_CLEANUP for rw unless there is ->free_iovec set, so remove the optimisation of NULL checking it inline, kfree() will take care if that would ever be the case. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/a233dc655d3d45bd4f69b73d55a61de46d914415.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: track request creds with a flagPavel Begunkov1-8/+13
Currently, if req->creds is not NULL, then there are creds assigned. Track the invariant with a new flag in req->flags. No need to clear the field at init, and also cleanup can be efficiently moved into io_clean_op(). Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/5f8baeb8d3b909487f555542350e2eac97005556.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: move creds from io-wq work to io_kiocbPavel Begunkov1-11/+13
io-wq now doesn't have anything to do with creds now, so move ->creds from struct io_wq_work into request (aka struct io_kiocb). Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/8520c72ab8b8f4b96db12a228a2ab4c094ae64e1.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18io_uring: refactor io_submit_flush_completions()Pavel Begunkov1-7/+6
struct io_comp_state is always contained in struct io_ring_ctx, don't pass them into io_submit_flush_completions() separately, it makes the interface cleaner and simplifies it for the compiler. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/44d6ca57003a82484338e95197024dbd65a1b376.1623949695.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-17io_uring: allow user configurable IO thread CPU affinityJens Axboe1-0/+51
io-wq defaults to per-node masks for IO workers. This works fine by default, but isn't particularly handy for workloads that prefer more specific affinities, for either performance or isolation reasons. This adds IORING_REGISTER_IOWQ_AFF that allows the user to pass in a CPU mask that is then applied to IO thread workers, and an IORING_UNREGISTER_IOWQ_AFF that simply resets the masks back to the default of per-node. Note that no care is given to existing IO threads, they will need to go through a reschedule before the affinity is correct if they are already running or sleeping. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-16io_uring: Add to traces the req pointer when availableOlivier Langlois1-5/+6
The req pointer uniquely identify a specific request. Having it in traces can provide valuable insights that is not possible to have if the calling process is reusing the same user_data value. Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Olivier Langlois <olivier@trillion01.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: optimise io_commit_cqring()Pavel Begunkov1-7/+11
In most cases io_commit_cqring() is just an smp_store_release(), and it's hot enough, especially for IRQ rw, to want it to save on a function call. Mark it inline and extract a non-inlined slow path doing drain and timeout flushing. The inlined part is pretty slim to not cause binary bloating. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/7350f8b6b92caa50a48a80be39909f0d83eddd93.1623772051.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: shove more drain bits out of hot pathPavel Begunkov1-20/+22
Place all drain_next logic into io_drain_req(), so it's never executed if there was no drained requests before. The only thing we need is to set ->drain_active if we see a request with IOSQE_IO_DRAIN, do that in io_init_req() where flags are definitely in registers. Also, all drain-related code is encapsulated in io_drain_req(), makes it cleaner. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/68bf4f7395ddaafbf1a26bd97b57d57d45a9f900.1623772051.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: switch !DRAIN fast path when possiblePavel Begunkov1-6/+8
->drain_used is one way, which is not optimal if users use DRAIN but very rarely. However, we can just clear it in io_drain_req() when all drained before requests are gone. Also rename the flag to reflect the change and be more clear about it. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/7f37a240857546a94df6348507edddacab150460.1623772051.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: fix min types mismatch in table allocPavel Begunkov1-1/+1
fs/io_uring.c: In function 'io_alloc_page_table': include/linux/minmax.h:20:28: warning: comparison of distinct pointer types lacks a cast Cast everything to size_t using min_t. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Fixes: 9123c8ffce16 ("io_uring: add helpers for 2 level table alloc") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/50f420a956bca070a43810d4a805293ed54f39d8.1623759527.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: Fix comment of io_get_sqeFam Zheng1-1/+1
The sqe_ptr argument has been gone since 709b302faddf (io_uring: simplify io_get_sqring, 2020-04-08), made the return value of the function. Update the comment accordingly. Signed-off-by: Fam Zheng <fam.zheng@bytedance.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/20210604164256.12242-1-fam.zheng@bytedance.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: optimise non-drain pathPavel Begunkov1-27/+30
Replace drain checks with one-way flag set upon seeing the first IOSQE_IO_DRAIN request. There are several places where it cuts cycles well: 1) It's much faster than the fast check with two conditions in io_drain_req() including pretty complex list_empty_careful(). 2) We can mark io_queue_sqe() inline now, that's a huge win. 3) It replaces timeout and drain checks in io_commit_cqring() with a single flags test. Also great not touching ->defer_list there without a reason so limiting cache bouncing. It adds a small amount of overhead to drain path, but it's negligible. The main nuisance is that once it meets any DRAIN request in io_uring instance lifetime it will _always_ go through a slower path, so drain-less and offset-mode timeout less applications are preferable. The overhead in that case would be not big, but it's worth to bear in mind. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/98d2fff8c4da5144bb0d08499f591d4768128ea3.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: refactor io_req_defer()Pavel Begunkov1-20/+19
Rename io_req_defer() into io_drain_req() and refactor it uncoupling it from io_queue_sqe() error handling and preparing for coming optimisations. Also, prioritise non IOSQE_ASYNC path. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/4f17dd56e7fbe52d1866f8acd8efe3284d2bebcb.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: move uring_lock locationPavel Begunkov1-9/+7
->uring_lock is prevalently used for submission, even though it protects many other things like iopoll, registeration, selected bufs, and more. And it's placed together with ->cq_wait poked on completion and CQ waiting sides. Move them apart, ->uring_lock goes to the submission data, and cq_wait to completion related chunk. The last one requires some reshuffling so everything needed by io_cqring_ev_posted*() is in one cacheline. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/dea5e845caee4c98aa0922b46d713154d81f7bd8.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: wait heads renamingPavel Begunkov1-15/+15
We use several wait_queue_head's for different purposes, but namings are confusing. First rename ctx->cq_wait into ctx->poll_wait, because this one is used for polling an io_uring instance. Then rename ctx->wait into ctx->cq_wait, which is responsible for CQE waiting. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/47b97a097780c86c67b20b6ccc4e077523dce682.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: clean up check_overflow flagPavel Begunkov1-11/+9
There are no users of ->sq_check_overflow, only ->cq_check_overflow is used. Combine it and move out of completion related part of struct io_ring_ctx. A not so obvious benefit of it is fitting all completion side fields into a single cacheline. It was taking 2 lines before with 56B padding, and io_cqring_ev_posted*() were still touching both of them. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/25927394964df31d113e3c729416af573afff5f5.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: small io_submit_sqe() optimisationPavel Begunkov1-1/+1
submit_state.link is used only to assemble a link and not used for actual submission, so clear it before io_queue_sqe() in io_submit_sqe(), awhile it's hot and in caches and queueing doesn't spoil it. May also potentially help compiler with spilling or to do other optimisations. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/1579939426f3ad6b55af3005b1389bbbed7d780d.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: optimise completion timeout flushingPavel Begunkov1-4/+6
io_commit_cqring() might be very hot and we definitely don't want to touch ->timeout_list there, because 1) it's shared with the submission side so might lead to cache bouncing and 2) may need to load an extra cache line, especially for IRQ completions. We're interested in it at the completion side only when there are offset-mode timeouts, which are not so popular. Replace list_empty(->timeout_list) hot path check with a new one-way flag, which is set when we prepare the first offset-mode timeout. note: the flag sits in the same line as briefly used after ->rings Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/e4892ec68b71a69f92ffbea4a1499be3ec0d463b.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: don't cache number of dropped SQEsPavel Begunkov1-7/+5
Kill ->cached_sq_dropped and wire DRAIN sequence number correction via ->cq_extra, which is there exactly for that purpose. User visible dropped counter will be populated by incrementing it instead of keeping a copy, similarly as it was done not so long ago with cq_overflow. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/088aceb2707a534d531e2770267c4498e0507cc1.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: refactor io_get_sqe()Pavel Begunkov1-2/+2
The line of io_get_sqe() evaluating @head consists of too many operations including READ_ONCE(), it's not convenient for probing. Refactor it also improving readability. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/866ad6e4ef4851c7c61f6b0e08dbd0a8d1abce84.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: shuffle more fields into SQ ctx sectionPavel Begunkov1-18/+17
Since moving locked_free_* out of struct io_submit_state ctx->submit_state is accessed on submission side only, so move it into the submission section. Same goes for rsrc table pointers/nodes/etc., they must be taken and checked during submission because sync'ed by uring_lock, so move them there as well. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/8a5899a50afc6ccca63249e716f580b246f3dec6.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: move ctx->flags from SQ cachelinePavel Begunkov1-4/+4
ctx->flags are heavily used by both, completion and submission sides, so move it out from the ctx fields related to submissions. Instead, place it together with ctx->refs, because it's already cacheline-aligned and so pads lots of space, and both almost never change. Also, in most occasions they are accessed together as refs are taken at submission time and put back during completion. Do same with ctx->rings, where the pointer itself is never modified apart from ring init/free. Note: in percpu mode, struct percpu_ref doesn't modify the struct itself but takes indirection with ref->percpu_count_ptr. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/4c48c173e63d35591383ba2b87e8b8e8dfdbd23d.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: keep SQ pointers in a single cachelinePavel Begunkov1-2/+1
sq_array and sq_sqes are always used together, however they are in different cachelines, where the borderline is right before cq_overflow_list is rather rarely touched. Move the fields together so it loads only one cacheline. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/3ef2411a94874da06492506a8897eff679244f49.1623709150.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-15io_uring: Fix incorrect sizeof operator for copy_from_user callColin Ian King1-2/+4
Static analysis is warning that the sizeof being used is should be of *data->tags[i] and not data->tags[i]. Although these are the same size on 64 bit systems it is not a portable assumption to assume this is true for all cases. Fix this by using a temporary pointer tag_slot to make the code a clearer. Addresses-Coverity: ("Sizeof not portable") Fixes: d878c81610e1 ("io_uring: hide rsrc tag copy into generic helpers") Signed-off-by: Colin Ian King <colin.king@canonical.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/20210615130011.57387-1-colin.king@canonical.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-14io_uring: inline io_iter_do_read()Pavel Begunkov1-1/+1
There are only two calls in source code of io_iter_do_read(), the function is small and pretty hot though is failed to get inlined. Makr it as inline. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/25a26dae7660da73fbc2244b361b397ef43d3caf.1623634182.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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