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

Bernd Schubert
2023-03-27T14:02:54Z

On 3/27/23 15:22, Pavel Begunkov wrote:
> 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.
>

I'm going to check where and why it hangs, busy with something else
today - by tomorrow I should know what happens.

Thanks,
Bernd