From: Stefan Hajnoczi <stefanha@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
qemu-block@nongnu.org, qemu-devel@nongnu.org, fam@euphon.net,
f.ebner@proxmox.com
Subject: Re: [PATCH 1/2] fdmon-io_uring: notify main loop when SQEs are queued
Date: Wed, 18 Feb 2026 10:56:45 -0500 [thread overview]
Message-ID: <20260218155645.GA587447@fedora> (raw)
In-Reply-To: <aY9Lj1BTVRCFyfic@redhat.com>
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On Fri, Feb 13, 2026 at 05:04:31PM +0100, Kevin Wolf wrote:
> Am 13.02.2026 um 15:26 hat Jens Axboe geschrieben:
> > When a vCPU thread handles MMIO (holding BQL), aio_co_enter() runs the
> > block I/O coroutine inline on the vCPU thread because
> > qemu_get_current_aio_context() returns the main AioContext when BQL is
> > held. The coroutine calls luring_co_submit() which queues an SQE via
> > fdmon_io_uring_add_sqe(), but the actual io_uring_submit() only happens
> > in gsource_prepare() on the main loop thread.
>
> Ouch! Yes, looks like we completely missed I/O submitted in vCPU threads
> in the recent changes (or I guess worker threads in theory, but I don't
> think there any that actually make use of aio_add_sqe()).
Worker threads don't have an AioContext, so they cannot call
aio_add_sqe().
Stefan
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next prev parent reply other threads:[~2026-02-18 15:58 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-13 14:26 [PATCHSET 0/2] io_uring fixes Jens Axboe
2026-02-13 14:26 ` [PATCH 1/2] fdmon-io_uring: notify main loop when SQEs are queued Jens Axboe
2026-02-13 16:04 ` Kevin Wolf
2026-02-18 9:57 ` Fiona Ebner
2026-02-18 16:06 ` Stefan Hajnoczi
2026-02-18 16:17 ` Jens Axboe
2026-02-18 20:02 ` Stefan Hajnoczi
2026-02-18 16:11 ` Stefan Hajnoczi
2026-02-18 16:19 ` Jens Axboe
2026-02-18 16:41 ` [PATCH v2] aio-posix: " Jens Axboe
2026-02-18 20:57 ` Stefan Hajnoczi
2026-02-19 14:27 ` Jens Axboe
2026-02-19 15:49 ` Kevin Wolf
2026-02-23 13:53 ` Stefan Hajnoczi
2026-02-18 15:56 ` Stefan Hajnoczi [this message]
2026-02-13 14:26 ` [PATCH 2/2] fdmon-io_uring: check CQ ring directly in gsource_check Jens Axboe
2026-02-13 16:22 ` Kevin Wolf
2026-02-18 16:24 ` Stefan Hajnoczi
2026-02-18 10:07 ` [PATCHSET 0/2] io_uring fixes Fiona Ebner
2026-03-03 11:52 ` Fiona Ebner
2026-03-03 16:51 ` Jens Axboe
2026-03-08 12:11 ` Michael Tokarev
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