Re: [RFC 4/4] io_uring: implement futex wait

[Pavel Begunkov]

On 6/1/21 4:45 PM, Jens Axboe wrote:
> On 6/1/21 8:58 AM, Pavel Begunkov wrote:
>> Add futex wait requests, those always go through io-wq for simplicity.
> 
> Not a huge fan of that, I think this should tap into the waitqueue
> instead and just rely on the wakeup callback to trigger the event. That
> would be a lot more efficient than punting to io-wq, both in terms of
> latency on trigger, but also for efficiency if the app is waiting on a
> lot of futexes.

Yes, that would be preferable, but looks futexes don't use
waitqueues but some manual enqueuing into a plist_node, see
futex_wait_queue_me() or mark_wake_futex().
Did I miss it somewhere?

-- 
Pavel Begunkov