Re: [PATCH 06/13] fuse: Add an interval ring stop worker/monitor

Pavel Begunkov
2023-03-27T13:24:57Z

On 3/23/23 20:51, Bernd Schubert wrote:
> On 3/23/23 14:18, Bernd Schubert wrote:
>> On 3/23/23 13:35, Miklos Szeredi wrote:
>>> On Thu, 23 Mar 2023 at 12:04, Bernd Schubert <bschubert@ddn.com> wrote:
[...]
> Found the reason why I complete SQEs when the daemon stops - on daemon
> side I have
>
> ret = io_uring_wait_cqe(&queue->ring, &cqe);
>
> and that hangs when you stop user side with SIGTERM/SIGINT. Maybe that
> could be solved with io_uring_wait_cqe_timeout() /
> io_uring_wait_cqe_timeout(), but would that really be a good solution?

It can be some sort of an eventfd triggered from the signal handler
and waited upon by an io_uring poll/read request. Or maybe signalfd.

> We would now have CPU activity in intervals on the daemon side for now
> good reason - the more often the faster SIGTERM/SIGINT works.
> So at best, it should be uring side that stops to wait on a receiving a
> signal.

FWIW, io_uring (i.e. kernel side) will stop waiting if there are pending
signals, and we'd need to check liburing to honour it, e.g. not to retry
waiting.

--
Pavel Begunkov