- 18 Jun, 2021 11 commits
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Pavel Begunkov authored
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.comSigned-off-by:
Jens Axboe <axboe@kernel.dk>
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
Inline __tctx_task_work() into tctx_task_work() in preparation for further optimisations. Signed-off-by:
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Pavel Begunkov authored
Clean up io_get_sequence() and add a comment describing the magic around sequence correction. Signed-off-by:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
WARNING: CPU: 1 PID: 11749 at fs/io-wq.c:244 io_wqe_wake_worker fs/io-wq.c:244 [inline] WARNING: CPU: 1 PID: 11749 at fs/io-wq.c:244 io_wqe_enqueue+0x7f6/0x910 fs/io-wq.c:751 A WARN_ON_ONCE() in io_wqe_wake_worker() can be triggered by a valid userspace setup. Replace it with pr_warn. Reported-by: syzbot+ea2f1484cffe5109dc10@syzkaller.appspotmail.com Signed-off-by:
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- 17 Jun, 2021 2 commits
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Jens Axboe authored
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 authored
In preparation for allowing user specific CPU masks for IO thread creation, switch to using a mask embedded in the per-node wqe structure. Signed-off-by:
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- 16 Jun, 2021 3 commits
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Olivier Langlois authored
mm related header files are not needed for io-wq module. remove them for a small clean-up. Reviewed-by:
Olivier Langlois <olivier@trillion01.com> Signed-off-by:
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Olivier Langlois authored
Fix tabulation to make nice columns Reviewed-by:
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Olivier Langlois authored
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:
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- 15 Jun, 2021 19 commits
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
->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:
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Pavel Begunkov authored
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: 9123c8ff ("io_uring: add helpers for 2 level table alloc") Signed-off-by:
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Fam Zheng authored
The sqe_ptr argument has been gone since 709b302f (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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
->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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
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:
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Colin Ian King authored
The variable ret is being initialized with a value that is never read, the assignment is redundant and can be removed. Addresses-Coverity: ("Unused value") Signed-off-by:Colin Ian King <colin.king@canonical.com> Link: https://lore.kernel.org/r/20210615143424.60449-1-colin.king@canonical.comSigned-off-by:
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Colin Ian King authored
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: d878c816 ("io_uring: hide rsrc tag copy into generic helpers") Signed-off-by:
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- 14 Jun, 2021 5 commits
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Pavel Begunkov authored
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:
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Pavel Begunkov authored
Merge io_uring_cancel_sqpoll() and __io_uring_cancel() as it's easier to have a conditional ctx traverse inside than keeping them in sync. Signed-off-by:
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Pavel Begunkov authored
tctx in submission part is always synchronised because is executed from the task's context, so we can batch allocate tctx/task references and store them across syscall boundaries. It avoids enough of operations, including an atomic for getting task ref and a percpu_counter_add() function call, which still fallback to spinlock for large batching cases (around >=32). Should be good for SQPOLL submitting in small portions and coming at some moment bpf submissions. Signed-off-by:
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Pavel Begunkov authored
We don't really need vmalloc for keeping tags, it's not a hot path and is there out of convenience, so replace it with two level tables to not litter kernel virtual memory mappings. Signed-off-by:
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Pavel Begunkov authored
Some parts like fixed file table use 2 level tables, factor out helpers for allocating/deallocating them as more users are to come. Signed-off-by:
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