Re: [PATCH] io_uring: add io_uring_enter(2) fixed file support

Pavel Begunkov
2022-03-04T02:33:29Z

On 3/4/22 02:18, Jens Axboe wrote:
> On 3/3/22 6:49 PM, Pavel Begunkov wrote:
>> On 3/3/22 16:31, Jens Axboe wrote:
>>> On 3/3/22 7:40 AM, Jens Axboe wrote:
>>>> On 3/3/22 7:36 AM, Jens Axboe wrote:
>>>>> The only potential oddity here is that the fd passed back is not a
>>>>> legitimate fd. io_uring does support poll(2) on its file descriptor, so
>>>>> that could cause some confusion even if I don't think anyone actually
>>>>> does poll(2) on io_uring.
>>>>
[...]
>>> which is about a 15% improvement, pretty massive...
>>
>> Is the bench single threaded (including io-wq)? Because if it
>> is, get/put shouldn't do any atomics and I don't see where the
>> result comes from.
>
> Yes, it has a main thread and IO threads. Which is not uncommon, most
> things are multithreaded these days...

They definitely are, just was confused by the bench as I can't
recall t/io_uring having >1 threads for nops and/or direct bdev I/O

--
Pavel Begunkov