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2022-10-27block/io_uring: revert "Use io_uring_register_ring_fd() to skip fd operations"Sam Li1-12/+1
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1193 The commit "Use io_uring_register_ring_fd() to skip fd operations" broke when booting a guest with iothread and io_uring. That is because the io_uring_register_ring_fd() call is made from the main thread instead of IOThread where io_uring_submit() is called. It can not be guaranteed to register the ring fd in the correct thread or unregister the same ring fd if the IOThread is disabled. This optimization is not critical so we will revert previous commit. This reverts commit e2848bc574fe2715c694bf8fe9a1ba7f78a1125a and 77e3f038af1764983087e3551a0fde9951952c4d. Cc: qemu-stable@nongnu.org Signed-off-by: Sam Li <faithilikerun@gmail.com> Message-Id: <20220924144815.5591-1-faithilikerun@gmail.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Tested-by: Dario Faggioli <dfaggioli@suse.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-08-02block/io_uring: add missing include fileJinhao Fan1-0/+1
The commit "Use io_uring_register_ring_fd() to skip fd operations" uses warn_report but did not include the header file "qemu/error-report.h". This causes "error: implicit declaration of function ‘warn_report’". Include this header file. Fixes: e2848bc574 ("Use io_uring_register_ring_fd() to skip fd operations") Signed-off-by: Jinhao Fan <fanjinhao21s@ict.ac.cn> Message-Id: <20220721065645.577404-1-fanjinhao21s@ict.ac.cn> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-07-07block/io_uring: clarify that short reads can happenStefan Hajnoczi1-6/+2
Jens Axboe has confirmed that short reads are rare but can happen: https://lore.kernel.org/io-uring/YsU%2FCGkl9ZXUI+Tj@stefanha-x1.localdomain/T/#m729963dc577d709b709c191922e98ec79d7eef54 The luring_resubmit_short_read() comment claimed they were only due to a specific io_uring bug that was fixed in Linux commit 9d93a3f5a0c ("io_uring: punt short reads to async context"), which is wrong. Dominique Martinet found that a btrfs bug also causes short reads. There may be more kernel code paths that result in short reads. Let's consider short reads fair game. Cc: Dominique Martinet <dominique.martinet@atmark-techno.com> Based-on: <20220630010137.2518851-1-dominique.martinet@atmark-techno.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Message-id: 20220706080341.1206476-1-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-07-07io_uring: fix short read slow pathDominique Martinet1-2/+2
sqeq.off here is the offset to read within the disk image, so obviously not 'nread' (the amount we just read), but as the author meant to write its current value incremented by the amount we just read. Normally recent versions of linux will not issue short reads, but it can happen so we should fix this. This lead to weird image corruptions when short read happened Fixes: 6663a0a33764 ("block/io_uring: implements interfaces for io_uring") Link: https://lkml.kernel.org/r/YrrFGO4A1jS0GI0G@atmark-techno.com Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com> Message-Id: <20220630010137.2518851-1-dominique.martinet@atmark-techno.com> Reviewed-by: Hanna Reitz <hreitz@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-06-15Use io_uring_register_ring_fd() to skip fd operationsSam Li1-1/+11
Linux recently added a new io_uring(7) optimization API that QEMU doesn't take advantage of yet. The liburing library that QEMU uses has added a corresponding new API calling io_uring_register_ring_fd(). When this API is called after creating the ring, the io_uring_submit() library function passes a flag to the io_uring_enter(2) syscall allowing it to skip the ring file descriptor fdget()/fdput() operations. This saves some CPU cycles. Signed-off-by: Sam Li <faithilikerun@gmail.com> Message-id: 20220531105011.111082-1-faithilikerun@gmail.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-04-06Remove qemu-common.h include from most unitsMarc-André Lureau1-1/+0
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20220323155743.1585078-33-marcandre.lureau@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-12aio-posix: split poll check from ready handlerStefan Hajnoczi1-8/+11
Adaptive polling measures the execution time of the polling check plus handlers called when a polled event becomes ready. Handlers can take a significant amount of time, making it look like polling was running for a long time when in fact the event handler was running for a long time. For example, on Linux the io_submit(2) syscall invoked when a virtio-blk device's virtqueue becomes ready can take 10s of microseconds. This can exceed the default polling interval (32 microseconds) and cause adaptive polling to stop polling. By excluding the handler's execution time from the polling check we make the adaptive polling calculation more accurate. As a result, the event loop now stays in polling mode where previously it would have fallen back to file descriptor monitoring. The following data was collected with virtio-blk num-queues=2 event_idx=off using an IOThread. Before: 168k IOPS, IOThread syscalls: 9837.115 ( 0.020 ms): IO iothread1/620155 io_submit(ctx_id: 140512552468480, nr: 16, iocbpp: 0x7fcb9f937db0) = 16 9837.158 ( 0.002 ms): IO iothread1/620155 write(fd: 103, buf: 0x556a2ef71b88, count: 8) = 8 9837.161 ( 0.001 ms): IO iothread1/620155 write(fd: 104, buf: 0x556a2ef71b88, count: 8) = 8 9837.163 ( 0.001 ms): IO iothread1/620155 ppoll(ufds: 0x7fcb90002800, nfds: 4, tsp: 0x7fcb9f1342d0, sigsetsize: 8) = 3 9837.164 ( 0.001 ms): IO iothread1/620155 read(fd: 107, buf: 0x7fcb9f939cc0, count: 512) = 8 9837.174 ( 0.001 ms): IO iothread1/620155 read(fd: 105, buf: 0x7fcb9f939cc0, count: 512) = 8 9837.176 ( 0.001 ms): IO iothread1/620155 read(fd: 106, buf: 0x7fcb9f939cc0, count: 512) = 8 9837.209 ( 0.035 ms): IO iothread1/620155 io_submit(ctx_id: 140512552468480, nr: 32, iocbpp: 0x7fca7d0cebe0) = 32 174k IOPS (+3.6%), IOThread syscalls: 9809.566 ( 0.036 ms): IO iothread1/623061 io_submit(ctx_id: 140539805028352, nr: 32, iocbpp: 0x7fd0cdd62be0) = 32 9809.625 ( 0.001 ms): IO iothread1/623061 write(fd: 103, buf: 0x5647cfba5f58, count: 8) = 8 9809.627 ( 0.002 ms): IO iothread1/623061 write(fd: 104, buf: 0x5647cfba5f58, count: 8) = 8 9809.663 ( 0.036 ms): IO iothread1/623061 io_submit(ctx_id: 140539805028352, nr: 32, iocbpp: 0x7fd0d0388b50) = 32 Notice that ppoll(2) and eventfd read(2) syscalls are eliminated because the IOThread stays in polling mode instead of falling back to file descriptor monitoring. As usual, polling is not implemented on Windows so this patch ignores the new io_poll_read() callback in aio-win32.c. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Message-id: 20211207132336.36627-2-stefanha@redhat.com [Fixed up aio_set_event_notifier() calls in tests/unit/test-fdmon-epoll.c added after this series was queued. --Stefan] Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2021-07-29block/io_uring: resubmit when result is -EAGAINFabian Ebner1-1/+15
Linux SCSI can throw spurious -EAGAIN in some corner cases in its completion path, which will end up being the result in the completed io_uring request. Resubmitting such requests should allow block jobs to complete, even if such spurious errors are encountered. Co-authored-by: Stefan Hajnoczi <stefanha@gmail.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Fabian Ebner <f.ebner@proxmox.com> Message-id: 20210729091029.65369-1-f.ebner@proxmox.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2020-11-17io_uring: do not use pointer after freePaolo Bonzini1-1/+1
Even though only the pointer value is only printed, it is untidy and Coverity complains. Cc: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20201113154102.1460459-1-pbonzini@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-06-05io_uring: use io_uring_cq_ready() to check for ready cqesStefano Garzarella1-6/+3
In qemu_luring_poll_cb() we are not using the cqe peeked from the CQ ring. We are using io_uring_peek_cqe() only to see if there are cqes ready, so we can replace it with io_uring_cq_ready(). Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Message-id: 20200519134942.118178-1-sgarzare@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2020-06-05io_uring: retry io_uring_submit() if it fails with errno=EINTRStefano Garzarella1-1/+1
As recently documented [1], io_uring_enter(2) syscall can return an error (errno=EINTR) if the operation was interrupted by a delivery of a signal before it could complete. This should happen when IORING_ENTER_GETEVENTS flag is used, for example during io_uring_submit_and_wait() or during io_uring_submit() when IORING_SETUP_IOPOLL is enabled. We shouldn't have this problem for now, but it's better to prevent it. [1] https://github.com/axboe/liburing/commit/344355ec6619de8f4e64584c9736530b5346e4f4 Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Message-id: 20200519133041.112138-1-sgarzare@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2020-02-18block/io_uring: Remove superfluous semicolonPhilippe Mathieu-Daudé1-1/+1
Fixes: 6663a0a3376 Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-Id: <20200218094402.26625-5-philmd@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-01-30block/io_uring: adds userspace completion pollingAarushi Mehta1-1/+16
Signed-off-by: Aarushi Mehta <mehta.aaru20@gmail.com> Acked-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20200120141858.587874-11-stefanha@redhat.com Message-Id: <20200120141858.587874-11-stefanha@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2020-01-30block: add trace events for io_uringAarushi Mehta1-3/+20
Signed-off-by: Aarushi Mehta <mehta.aaru20@gmail.com> Acked-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20200120141858.587874-10-stefanha@redhat.com Message-Id: <20200120141858.587874-10-stefanha@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2020-01-30block/io_uring: implements interfaces for io_uringAarushi Mehta1-0/+401
Aborts when sqe fails to be set as sqes cannot be returned to the ring. Adds slow path for short reads for older kernels Signed-off-by: Aarushi Mehta <mehta.aaru20@gmail.com> Acked-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20200120141858.587874-5-stefanha@redhat.com Message-Id: <20200120141858.587874-5-stefanha@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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