- 23 Aug, 2021 40 commits
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Pavel Begunkov authored
If a requests is forwarded into io-wq, there is a good chance it hasn't been refcounted yet and we can save one req_ref_get() by setting the refcount number to the right value directly. Signed-off-by:
Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/2d53f4449faaf73b4a4c5de667fc3c176d974860.1628981736.git.asml.silence@gmail.comSigned-off-by:
Jens Axboe <axboe@kernel.dk>
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Jens Axboe authored
io_req_free_batch() has a __must_hold annotation referencing a request being passed in, but we're passing in the context. Signed-off-by: -
Hao Xu authored
We can merge two spin_unlock() operations to one since we removed some code not long ago. Signed-off-by:
Hao Xu <haoxu@linux.alibaba.com> Signed-off-by:
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Hao Xu authored
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:
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Hao Xu authored
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:
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Pavel Begunkov authored
io_prep_linked_timeout() grew too heavy and compiler now refuse to inline the function. Help it by splitting in two and annotating with inline. Signed-off-by:
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Pavel Begunkov authored
As submission references are gone, there is only one initial reference left. Instead of actually doing atomic refcounting, add a flag indicating whether we're going to take more refs or doing any other sync magic. The flag should be set before the request may get used in parallel. Together with the previous patch it saves 2 refcount atomics per request for IOPOLL and IRQ completions, and 1 atomic per req for inline completions, with some exceptions. In particular, currently, there are three cases, when the refcounting have to be enabled: - Polling, including apoll. Because double poll entries takes a ref. Might get relaxed in the near future. - Link timeouts, enabled for both, the timeout and the request it's bound to, because they work in-parallel and we need to synchronise to cancel one of them on completion. - When a request gets in io-wq, because it doesn't hold uring_lock and we need guarantees of submission references. Signed-off-by:
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Pavel Begunkov authored
Requests are by default given with two references, submission and completion. Completion references are straightforward, they represent request ownership and are put when a request is completed or so. Submission references are a bit more trickier. They're needed when io_issue_sqe() followed deep into the submission stack (e.g. in fs, block, drivers, etc.), request may have given away for concurrent execution or already completed, and the code unwinding back to io_issue_sqe() may be accessing some pieces of our requests, e.g. file or iov. Now, we prevent such async/in-depth completions by pushing requests through task_work. Punting to io-wq is also done through task_works, apart from a couple of cases with a pretty well known context. So, there're two cases: 1) io_issue_sqe() from the task context and protected by ->uring_lock. Either requests return back to io_uring or handed to task_work, which won't be executed because we're currently controlling that task. So, we can be sure that requests are staying alive all the time and we don't need submission references to pin them. 2) io_issue_sqe() from io-wq, which doesn't hold the mutex. The role of submission reference is played by io-wq reference, which is put by io_wq_submit_work(). Hence, it should be fine. Considering that, we can carefully kill the submission reference. Signed-off-by:
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Pavel Begunkov authored
Soon, we won't need to put several references at once, remove req_ref_sub_and_test() and @nr argument from io_put_req_deferred(), and put the rest of the references by hand. Signed-off-by:
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Pavel Begunkov authored
Move all request refcount helpers to avoid forward declarations in the future. Signed-off-by:
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Jens Axboe authored
We have no hard/soft IRQ users of this lock left, remove any IRQ disabling/saving and restoring when grabbing this lock. This is straight forward with no users entering with IRQs disabled anymore, the only thing to look out for is the waitqueue poll head lock which nests inside the completion lock. That needs IRQs disabled, and hence we have to do that now instead of relying on the outer lock doing so. Signed-off-by: -
Jens Axboe authored
This is in preparation to making the completion lock work outside of hard/soft IRQ context. Signed-off-by: -
Jens Axboe authored
This is in preparation to making the completion lock work outside of hard/soft IRQ context. Signed-off-by: -
Jens Axboe authored
This is in preparation to making the completion lock work outside of hard/soft IRQ context. Add a timeout_lock to handle the ordering of timeout completions or cancelations with the timeouts actually triggering. Signed-off-by: -
Pavel Begunkov authored
For requests with non-fixed files, instead of grabbing just one reference, we get by the number of left requests, so the following requests using the same file can take it without atomics. However, it's not all win. If there is one request in the middle not using files or having a fixed file, we'll need to put back the left references. Even worse if an application submits requests dealing with different files, it will do a put for each new request, so doubling the number of atomics needed. Also, even if not used, it's still takes some cycles in the submission path. If a file used many times, it rather makes sense to pre-register it, if not, we may fall in the described pitfall. So, this optimisation is a matter of use case. Go with the simpliest code-wise way, remove it. Signed-off-by:
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Pavel Begunkov authored
After recent fixes, tctx_task_work() always does proper spinlocking before looking into ->task_list, so now we don't need atomics for ->task_state, replace it with non-atomic task_running using the critical section. Tide it up, combine two separate block with spinlocking, and always try to splice in there, so we do less locking when new requests are arriving during the function execution. Signed-off-by:
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Pavel Begunkov authored
Inline io_poll_remove_waitqs() into its only user and clean it up. Signed-off-by:
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Pavel Begunkov authored
Unlike __io_cqring_overflow_flush(), nobody does forced flushing with io_cqring_overflow_flush(), so removed the argument from it. Signed-off-by:
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Pavel Begunkov authored
Inline struct io_comp_state into struct io_submit_state. They are already coupled tightly, together with mixed responsibilities it only brings confusion having them separately. Signed-off-by:
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Pavel Begunkov authored
req->compl.list is used to cache freed requests, and so can't overlap in time with req->inflight_entry. So, use inflight_entry to link requests and remove compl.list. Signed-off-by:
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Pavel Begunkov authored
We don't use @tsk argument of io_req_cache_free(), remove it. Signed-off-by:
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Pavel Begunkov authored
Don't kfree requests in __io_free_req() but put them back into the internal request cache. That makes allocations more sustainable and will be used for refcounting optimisations. Signed-off-by:
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Pavel Begunkov authored
Move io_fallback_req_func() to kill yet another forward declaration. Signed-off-by:
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Pavel Begunkov authored
We cache all the reference to task + tctx, so if io_put_task() is called by the corresponding task itself, we can save on atomics and return the refs right back into the cache. It's beneficial for all inline completions, and also iopolling, when polling and submissions are done by the same task, including SQPOLL|IOPOLL. Note: io_uring_cancel_generic() can return refs to the cache as well, so those should be flushed in the loop for tctx_inflight() to work right. Signed-off-by:
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Pavel Begunkov authored
In case of on-exec io_uring cancellations, tasks already wait for all submitted requests to get completed/cancelled, so we don't need to check for ->in_execve separately. Signed-off-by:
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Pavel Begunkov authored
IO_IOPOLL_BATCH is not used, delete it. Signed-off-by:
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Pavel Begunkov authored
If io_ring_exit_work() can't get it done in 5 minutes, something is going very wrong, don't keep spinning at HZ / 20 rate, it doesn't help and it may take much of CPU time if there is a lot of workers stuck as such. Signed-off-by:
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Pavel Begunkov authored
Move IORING_SETUP_IOPOLL check into __io_openat_prep(), so both openat and openat2 reuse it. Signed-off-by:
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Pavel Begunkov authored
Inline io_free_req_deferred(), there is no reason to keep it separated. Signed-off-by:
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Pavel Begunkov authored
Move the function together with io_rsrc_node_ref_zero() in the source file as it is to get rid of forward declarations. Signed-off-by:
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Pavel Begunkov authored
Move the function in the source file as it is to get rid of forward declarations. Signed-off-by:
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Pavel Begunkov authored
Refactor __io_uring_register() by extracting a helper responsible for ctx queisce. Looks better and will make it easier to add more optimisations. Signed-off-by:
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Pavel Begunkov authored
Turns out we always init struct io_wait_queue in io_cqring_wait(), even if it's not used after, i.e. there are already enough of CQEs. And often it's exactly what happens, for instance, requests may have been completed inline, or in case of io_uring_enter(submit=N, wait=1). It shows up in my profiler, so optimise it by delaying the struct init. Signed-off-by:
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Pavel Begunkov authored
Add more annotations for submission path functions holding ->uring_lock. Signed-off-by:
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Pavel Begunkov authored
IOPOLL users should care more about getting completions for requests they submitted, but not in "device did/completed something". Currently, io_do_iopoll() may return a positive number, which will instruct io_iopoll_check() to break the loop and end the syscall, even if there is not enough CQEs or none at all. Don't return positive numbers, so io_iopoll_check() exits only when it gets an actual error, need reschedule or got enough CQEs. Signed-off-by:
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Pavel Begunkov authored
Replace the main if of io_flush_cached_reqs() with inverted condition + goto, so all the cases are handled in the same way. And also extract io_preinit_req() to make it cleaner and easier to refer to. Signed-off-by:
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Pavel Begunkov authored
Prepare nodes that we're going to add before actually linking them, it's always safer and costs us nothing. Signed-off-by:
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Pavel Begunkov authored
We prefer nornal task_works even if it would fail requests inside. Kill a PF_EXITING check in io_req_task_work_add(), task_work_add() handles well dying tasks, i.e. return error when can't enqueue due to late stages of do_exit(). Signed-off-by:
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Pavel Begunkov authored
Move io-wq callbacks closer to each other, so it's easier to work with them, and rename io_free_work() into io_wq_free_work() for consistency. Signed-off-by:
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Pavel Begunkov authored
If we use fixed files, we can be sure (almost) that REQ_F_ISREG is set. However, for non-reg files io_prep_rw() still will look into inode to double check, and that's expensive and can be avoided. The only caveat is that it only currently works with 64+ bit architectures, see FFS_ISREG, so we should consider that. Signed-off-by:
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