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2024-04-23io_uring/notif: implement notification stackingPavel Begunkov1-0/+3
The network stack allows only one ubuf_info per skb, and unlike MSG_ZEROCOPY, each io_uring zerocopy send will carry a separate ubuf_info. That means that send requests can't reuse a previosly allocated skb and need to get one more or more of new ones. That's fine for large sends, but otherwise it would spam the stack with lots of skbs carrying just a little data each. To help with that implement linking notification (i.e. an io_uring wrapper around ubuf_info) into a list. Each is refcounted by skbs and the stack as usual. additionally all non head entries keep a reference to the head, which they put down when their refcount hits 0. When the head have no more users, it'll efficiently put all notifications in a batch. As mentioned previously about ->io_link_skb, the callback implementation always allows to bind to an skb without a ubuf_info. Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/bf1e7f9b72f9ecc99999fdc0d2cded5eea87fd0b.1713369317.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-04-23io_uring/notif: simplify io_notif_flush()Pavel Begunkov1-6/+3
io_notif_flush() is partially duplicating io_tx_ubuf_complete(), so instead of duplicating it, make the flush call io_tx_ubuf_complete. Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/19e41652c16718b946a5c80d2ad409df7682e47e.1713369317.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-04-15io_uring/notif: shrink account_pages to u32Pavel Begunkov1-1/+2
->account_pages is the number of pages we account against the user derived from unsigned len, it definitely fits into unsigned, which saves some space in struct io_notif_data. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/19f2687fcb36daa74d86f4a27bfb3d35cffec318.1713185320.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-04-15io_uring/net: get rid of io_notif_complete_tw_extPavel Begunkov1-2/+4
io_notif_complete_tw_ext() can be removed and combined with io_notif_complete_tw to make it simpler without sacrificing anything. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/025a124a5e20e2474a57e2f04f16c422eb83063c.1712534031.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-04-15io_uring/notif: add constant for ubuf_info flagsPavel Begunkov1-0/+1
Add a constant IO_NOTIF_UBUF_FLAGS for struct ubuf_info flags that notifications use. That should minimise merge conflicts for planned changes touching both io_uring and net at the same time. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-04-07io_uring: reduce scheduling due to twPavel Begunkov1-1/+1
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: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/d2b77e99d1e86624d8a69f7037d764b739dcd225.1680782017.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-21io_uring: move zc reporting from the hot pathPavel Begunkov1-0/+1
Add custom tw and notif callbacks on top of usual bits also handling zc reporting. That moves it from the hot path. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/40de4a6409042478e1f35adc4912e23226cb1b5c.1667557923.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-21io_uring/net: inline io_notif_flush()Pavel Begunkov1-1/+10
io_notif_flush() is pretty simple, we can inline it. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/332359e7bd124138dfe51340bbec829c9b265c18.1667557923.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-21io_uring/net: introduce IORING_SEND_ZC_REPORT_USAGE flagStefan Metzmacher1-0/+3
It might be useful for applications to detect if a zero copy transfer with SEND[MSG]_ZC was actually possible or not. The application can fallback to plain SEND[MSG] in order to avoid the overhead of two cqes per request. Or it can generate a log message that could indicate to an administrator that no zero copy was possible and could explain degraded performance. Cc: stable@vger.kernel.org # 6.1 Link: https://lore.kernel.org/io-uring/fb6a7599-8a9b-15e5-9b64-6cd9d01c6ff4@gmail.com/T/#m2b0d9df94ce43b0e69e6c089bdff0ce6babbdfaa Signed-off-by: Stefan Metzmacher <metze@samba.org> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/8945b01756d902f5d5b0667f20b957ad3f742e5e.1666895626.git.metze@samba.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-01io_uring/net: simplify zerocopy send user APIPavel Begunkov1-41/+2
Following user feedback, this patch simplifies zerocopy send API. One of the main complaints is that the current API is difficult with the userspace managing notification slots, and then send retries with error handling make it even worse. Instead of keeping notification slots change it to the per-request notifications model, which posts both completion and notification CQEs for each request when any data has been sent, and only one CQE if it fails. All notification CQEs will have IORING_CQE_F_NOTIF set and IORING_CQE_F_MORE in completion CQEs indicates whether to wait a notification or not. IOSQE_CQE_SKIP_SUCCESS is disallowed with zerocopy sends for now. This is less flexible, but greatly simplifies the user API and also the kernel implementation. We reuse notif helpers in this patch, but in the future there won't be need for keeping two requests. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/95287640ab98fc9417370afb16e310677c63e6ce.1662027856.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-01io_uring/notif: remove notif registrationPavel Begunkov1-11/+0
We're going to remove the userspace exposed zerocopy notification API, remove notification registration. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/6ff00b97be99869c386958a990593c9c31cf105b.1662027856.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-08-16io_uring/notif: raise limit on notification slotsPavel Begunkov1-1/+1
1024 notification slots is rather an arbitrary value, raise it up, everything is accounted to memcg. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/eb78a0a5f2fa5941f8e845cdae5fb399bf7ba0be.1660566179.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-08-13io_uring: make io_kiocb_to_cmd() typesafeStefan Metzmacher1-1/+1
We need to make sure (at build time) that struct io_cmd_data is not casted to a structure that's larger. Signed-off-by: Stefan Metzmacher <metze@samba.org> Link: https://lore.kernel.org/r/c024cdf25ae19fc0319d4180e2298bade8ed17b8.1660201408.git.metze@samba.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-27io_uring: notification completion optimisationPavel Begunkov1-29/+13
We want to use all optimisations that we have for io_uring requests like completion batching, memory caching and more but for zc notifications. Fortunately, notification perfectly fit the request model so we can overlay them onto struct io_kiocb and use all the infratructure. Most of the fields of struct io_notif natively fits into io_kiocb, so we replace struct io_notif with struct io_kiocb carrying struct io_notif_data in the cmd cache line. Then we adapt io_alloc_notif() to use io_alloc_req()/io_alloc_req_refill(), and kill leftovers of hand coded caching. __io_notif_complete_tw() is converted to use io_uring's tw infra. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/9e010125175e80baf51f0ca63bdc7cc6a4a9fa56.1658913593.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring/net: make page accounting more consistentPavel Begunkov1-0/+19
Make network page accounting more consistent with how buffer registration is working, i.e. account all memory to ctx->user. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/4aacfe64bbb81b27f9ecf5d5c219c69a07e5aa56.1658742118.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring/net: improve io_get_notif_slot typesPavel Begunkov1-1/+1
Don't use signed int for slot indexing. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/e4d15aefebb5e55729dd9b5ec01ab16b70033343.1658742118.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: flush notifiers after sendzcPavel Begunkov1-0/+11
Allow to flush notifiers as a part of sendzc request by setting IORING_SENDZC_FLUSH flag. When the sendzc request succeedes it will flush the used [active] notifier. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/e0b4d9a6797e2fd6092824fe42953db7a519bbc8.1657643355.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: add notification slot registrationPavel Begunkov1-0/+3
Let the userspace to register and unregister notification slots. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/a0aa8161fe3ebb2a4cc6e5dbd0cffb96e6881cf5.1657643355.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: add rsrc referencing for notifiersPavel Begunkov1-0/+1
In preparation to zerocopy sends with fixed buffers make notifiers to reference the rsrc node to protect the used fixed buffers. We can't just grab it for a send request as notifiers can likely outlive requests that used it. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/3cd7a01d26837945b6982fa9cf15a63230f2ed4f.1657643355.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: complete notifiers in twPavel Begunkov1-0/+3
We need a task context to post CQEs but using wq is too expensive. Try to complete notifiers using task_work and fall back to wq if fails. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/089799ab665b10b78fdc614ae6d59fa7ef0d5f91.1657643355.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: cache struct io_notifPavel Begunkov1-0/+5
kmalloc'ing struct io_notif is too expensive when done frequently, cache them as many other resources in io_uring. Keep two list, the first one is from where we're getting notifiers, it's protected by ->uring_lock. The second is protected by ->completion_lock, to which we queue released notifiers. Then we splice one list into another when needed. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/9dec18f7fcbab9f4bd40b96e5ae158b119945230.1657643355.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: add zc notification infrastructurePavel Begunkov1-0/+64
Add internal part of send zerocopy notifications. There are two main structures, the first one is struct io_notif, which carries inside struct ubuf_info and maps 1:1 to it. io_uring will be binding a number of zerocopy send requests to it and ask to complete (aka flush) it. When flushed and all attached requests and skbs complete, it'll generate one and only one CQE. There are intended to be passed into the network layer as struct msghdr::msg_ubuf. The second concept is notification slots. The userspace will be able to register an array of slots and subsequently addressing them by the index in the array. Slots are independent of each other. Each slot can have only one notifier at a time (called active notifier) but many notifiers during the lifetime. When active, a notifier not going to post any completion but the userspace can attach requests to it by specifying the corresponding slot while issueing send zc requests. Eventually, the userspace will want to "flush" the notifier losing any way to attach new requests to it, however it can use the next atomatically added notifier of this slot or of any other slot. When the network layer is done with all enqueued skbs attached to a notifier and doesn't need the specified in them user data, the flushed notifier will post a CQE. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/3ecf54c31a85762bf679b0a432c9f43ecf7e61cc.1657643355.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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