- 12 Apr, 2023 9 commits
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Pavel Begunkov authored
SCM file accounting is a slow path and is only used for UNIX files. Extract a helper out of io_rsrc_file_put() that does the SCM unaccounting. Signed-off-by:
Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/58cc7bffc2ee96bec8c2b89274a51febcbfa5556.1681210788.git.asml.silence@gmail.comSigned-off-by:
Jens Axboe <axboe@kernel.dk>
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Pavel Begunkov authored
We use io_rsrc_node_switch() coupled with io_rsrc_node_switch_start() for a bunch of cases including initialising ctx->rsrc_node, i.e. by passing NULL instead of rsrc_data. Leave it to only deal with actual node changing. For that, first remove it from io_uring_create() and add a function allocating the first node. Then also remove all calls to io_rsrc_node_switch() from files/buffers register as we already have a node installed and it does essentially nothing. Signed-off-by:
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Pavel Begunkov authored
struct io_rsrc_node::rsrc_data field is initialised on rsrc removal and shouldn't be used before that, still let's play safe and zero the field on alloc. Signed-off-by:
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Pavel Begunkov authored
We store one pre-allocated rsrc node in ->rsrc_backup_node, merge it with ->rsrc_node_cache. Signed-off-by:
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Pavel Begunkov authored
Add a lockdep chek to make sure that file and buffer updates hold ->uring_lock. Signed-off-by:
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Pavel Begunkov authored
We don't post CQEs from the IRQ context, add a check catching that. Signed-off-by:
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Pavel Begunkov authored
The kernel test robot complains about __io_remove_buffers(). io_uring/kbuf.c:221 __io_remove_buffers() warn: variable dereferenced before check 'bl->buf_ring' (see line 219) That check is not needed as ->buf_ring will always be set, so we can remove it and so silence the warning. Signed-off-by:
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Pavel Begunkov authored
io_uring/io_uring.c:432 io_prep_async_work() error: we previously assumed 'req->file' could be null (see line 425). Even though it's a false positive as there will not be REQ_F_ISREG set without a file, let's add a simple check to make the kernel test robot happy. We don't care about performance here, but assumingly it'll be optimised out by the compiler. Signed-off-by:
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Jens Axboe authored
We know now what the completion context is for the uring_cmd completion handling, so use that to have io_req_task_complete() decide what the best way to complete the request is. This allows batching of the posted completions if we have multiple pending, rather than always doing them one-by-one. Signed-off-by:
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- 06 Apr, 2023 8 commits
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Pavel Begunkov authored
Chains of memory accesses are never good for performance. The req->task->io_uring->in_cancel in io_req_local_work_add() is there so that when a task is exiting via io_uring_try_cancel_requests() and starts waiting for completions, it gets woken up by every new task_work item queued. Do a little trick by announcing waiting in io_uring_try_cancel_requests(), making io_req_local_work_add() wake us up. We also need to check for deferred tw items after prepare_to_wait(TASK_INTERRUPTIBLE); Signed-off-by:
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Pavel Begunkov authored
Separate ->task_complete path in __io_cq_unlock_post_flush(). Signed-off-by:
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Pavel Begunkov authored
Every task_work will try to wake the task to be executed, which causes excessive scheduling and additional overhead. For some tw it's justified, but others won't do much but post a single CQE. When a task waits for multiple cqes, every such task_work will wake it up. Instead, the task may give a hint about how many cqes it waits for, io_req_local_work_add() will compare against it and skip wake ups if #cqes + #tw is not enough to satisfy the waiting condition. Task_work that uses the optimisation should be simple enough and never post more than one CQE. It's also ignored for non DEFER_TASKRUN rings. Signed-off-by:
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Pavel Begunkov authored
We'll need to grab some information from the previous request in the tw list, inline llist_add(), it'll be used in the following patch. Signed-off-by:
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Pavel Begunkov authored
We pass 'allow_local' into io_req_task_work_add() but will need more flags. Replace it with a flags bit field and name this allow_local flag. Signed-off-by:
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Pavel Begunkov authored
Instead of smp_mb() + __io_cqring_wake() in __io_cq_unlock_post_flush() use equivalent io_cqring_wake(). With that we can clean it up further and remove __io_cqring_wake(). Signed-off-by:
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Pavel Begunkov authored
We currently pin the ctx for io_req_local_work_add() with percpu_ref_get/put, which implies two rcu_read_lock/unlock pairs and some extra overhead on top in the fast path. Replace it with a pure rcu read and let io_ring_exit_work() synchronise against it. Signed-off-by:
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Pavel Begunkov authored
Move ctx pinning from io_req_local_work_add() to the caller, looks better and makes working with the code a bit easier. Signed-off-by:
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- 05 Apr, 2023 1 commit
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Jens Axboe authored
Rather than check this in the fast path issue, it makes more sense to just assign the copy of the data when we're setting it up anyway. This makes the code a bit cleaner, and removes the need for this check in the issue path. Reviewed-by:
Gabriel Krisman Bertazi <krisman@suse.de> Reviewed-by:
Keith Busch <kbusch@kernel.org> Signed-off-by:
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- 04 Apr, 2023 13 commits
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Pavel Begunkov authored
The number of entries in the rsrc node cache is limited to 512, which still seems unnecessarily large. Add per cache thresholds and set to to 32 for the rsrc node cache. Signed-off-by:
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Pavel Begunkov authored
Every struct io_rsrc_node takes a struct io_rsrc_data reference, which means all rsrc updates do 2 extra atomics. Replace atomics refcounting with a int as it's all done under ->uring_lock. Signed-off-by:
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Pavel Begunkov authored
We should hold ->uring_lock while putting nodes with io_put_rsrc_node(), add a lockdep check for that. Signed-off-by:
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Pavel Begunkov authored
Add allocation cache for struct io_rsrc_node, it's always allocated and put under ->uring_lock, so it doesn't need any extra synchronisation around caches. Signed-off-by:
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Pavel Begunkov authored
struct delayed_work rsrc_put_work was previously used to offload node freeing because io_rsrc_node_ref_zero() was previously called by RCU in the IRQ context. Now, as percpu refcounting is gone, we can do it eagerly at the spot without pushing it to a worker. Signed-off-by:
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Pavel Begunkov authored
Every io_rsrc_node keeps a list of items to put, and all entries are kmalloc()'ed. However, it's quite often to queue up only one entry per node, so let's add an inline entry there to avoid extra allocations. Signed-off-by:
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Pavel Begunkov authored
We have too many "rsrc" around which makes the name of struct io_rsrc_node::rsrc_list confusing. The field is responsible for keeping a list of files or buffers, so call it item_list and add comments around. Signed-off-by:
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Pavel Begunkov authored
We use ->rsrc_ref_lock spinlock to protect ->rsrc_ref_list in io_rsrc_node_ref_zero(). Now we removed pcpu refcounting, which means io_rsrc_node_ref_zero() is not executed from the irq context as an RCU callback anymore, and we also put it under ->uring_lock. io_rsrc_node_switch(), which queues up nodes into the list, is also protected by ->uring_lock, so we can safely get rid of ->rsrc_ref_lock. Signed-off-by:
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Pavel Begunkov authored
Currently, for nodes we have an atomic counter and some cached (non-atomic) refs protected by uring_lock. Let's put all ref manipulations under uring_lock and get rid of the atomic part. It's free as in all cases we care about we already hold the lock. Signed-off-by:
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Pavel Begunkov authored
io_free_req() is not often used but nevertheless problematic as there is no way to know the current context, it may be used from the submission path or even by an irq handler. Push it to a fresh context using task_work. Signed-off-by:
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Pavel Begunkov authored
io_req_put_rsrc() doesn't need any locking, so move it out of a spinlock section in __io_req_complete_post() and adjust helpers. Signed-off-by:
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Pavel Begunkov authored
We cache refs of the current node (i.e. ctx->rsrc_node) in ctx->rsrc_cached_refs. We'll be moving away from atomics, so move the cached refs in struct io_rsrc_node for now. It's a prep patch and shouldn't change anything in practise. Signed-off-by:
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Pavel Begunkov authored
One problem with the current rsrc infra is that often updates will generates lots of rsrc nodes, each carry pcpu refs. That takes quite a lot of memory, especially if there is a stall, and takes lots of CPU cycles. Only pcpu allocations takes >50 of CPU with a naive benchmark updating files in a loop. Replace pcpu refs with normal refcounting. There is already a hot path avoiding atomics / refs, but following patches will further improve it. Signed-off-by:
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- 03 Apr, 2023 9 commits
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Jens Axboe authored
We already do this manually for the !SQPOLL case, do it in general and we can also dump the ugly min3() in io_submit_sqes(). Signed-off-by: -
Jens Axboe authored
It has nothing to do with the SQE at this point, it's a request submission. While in there, get rid of the 'force_nonblock' argument which is also dead, as we only pass in true. Signed-off-by: -
Pavel Begunkov authored
For task works we're passing around a bool pointer for whether the current ring is locked or not, let's wrap it in a structure, that will make it more opaque preventing abuse and will also help us to pass more info in the future if needed. Signed-off-by:
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Pavel Begunkov authored
Before cond_resched()'ing in handle_tw_list() we also drop the current ring context, and so the next loop iteration will need to pick/pin a new context and do trylock. The chunk removed by this patch was intended to be an optimisation covering exactly this case, i.e. retaking the lock after reschedule, but in reality it's skipped for the first iteration after resched as described and will keep hammering the lock if it's contended. Signed-off-by:
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Jens Axboe authored
Since the move to PF_IO_WORKER, we don't juggle memory context manually anymore. Remove that outdated part of the comment for __io_worker_idle(). Signed-off-by: -
Pavel Begunkov authored
There are two leftover structures from the notification registration mechanism that has never been released, kill them. Signed-off-by:
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Gabriel Krisman Bertazi authored
Since commit 0654b05e7e65 ("io_uring: One wqe per wq"), we have just a single io_wqe instance embedded per io_wq. Drop the extra structure in favor of accessing struct io_wq directly, cleaning up quite a bit of dereferences and backpointers. No functional changes intended. Tested with liburing's testsuite and mmtests performance microbenchmarks. I didn't observe any performance regressions. Signed-off-by: -
Gabriel Krisman Bertazi authored
Since we now have a single io_wqe per io_wq instead of per-node, and in preparation to its removal, move the accounting into the parent structure. Signed-off-by:
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Jens Axboe authored
On at least parisc, we have strict requirements on how we virtually map an address that is shared between the application and the kernel. On these platforms, IOU_PBUF_RING_MMAP should be used when setting up a shared ring buffer for provided buffers. If the application is mapping these pages and asking the kernel to pin+map them as well, then we have no control over what virtual address we get in the kernel. For that case, do a sanity check if SHM_COLOUR is defined, and disallow the mapping request. The application must fall back to using IOU_PBUF_RING_MMAP for this case, and liburing will do that transparently with the set of helpers that it has. Signed-off-by:
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