Re: [PATCH] io_uring: trigger worker exit when ring is exiting

[Jens Axboe <axboe@kernel.dk>]

On 9/2/21 12:08 PM, Jens Axboe wrote:
> On 9/2/21 12:04 PM, Pavel Begunkov wrote:
>> On 9/2/21 6:56 PM, Jens Axboe wrote:
>>> If a task exits normally, then the teardown of async workers happens
>>> quickly. But if it simply closes the ring fd, then the async teardown
>>> ends up waiting for workers to timeout if they are sleeping, which can
>>> then take up to 5 seconds (by default). This isn't a big issue as this
>>> happens off the workqueue path, but let's be nicer and ensure that we
>>> exit as quick as possible.
>>
>> ring = io_uring_init();
>> ...
>> io_uring_close(&ring); // triggers io_ring_ctx_wait_and_kill()
>> rint2 = io_uring_init();
>> ...
>>
>> It looks IO_WQ_BIT_EXIT there will be troublesome.
> 
> I wonder if we can get by with just a wakeup. Let me test...

Nah not enough. Would be nice to fix though, pretty annoying that the
threads sit there for 5 seconds doing nothing.

-- 
Jens Axboe