Re: [ANNOUNCEMENT] io_uring SQPOLL sharing changes

[Joseph Qi <jiangqi903@gmail.com>]

On 3/24/21 12:22 AM, Jens Axboe wrote:
> On 3/22/21 10:09 PM, Joseph Qi wrote:
>>
>>
>> On 3/22/21 10:49 PM, Jens Axboe wrote:
>>> On 3/21/21 11:54 PM, Xiaoguang Wang wrote:
>>>> hi Pavel,
>>>>
>>>>> Hey,
>>>>>
>>>>> You may have already noticed, but there will be a change how SQPOLL
>>>>> is shared in 5.12. In particular, SQPOLL may be shared only by processes
>>>>> belonging to the same thread group. If this condition is not fulfilled,
>>>>> then it silently creates a new SQPOLL task.
>>>>
>>>> Thanks for your kindly reminder, currently we only share sqpoll thread
>>>> in threads belonging to one same process.
>>>
>>> That's good to know, imho it is also the only thing that _really_ makes
>>> sense to do.
>>>
>>> Since we're on the topic, are you actively using the percpu thread setup
>>> that you sent out patches for earlier? That could still work within
>>> the new scheme of having io threads, but I'd be curious to know first
>>> if you guys are actually using it.
>>>
>>
>> Yes, we've already used percpu sqthread feature in our production
>> environment, in which 16 application threads share the same sqthread,
>> and it gains ~20% rt improvement compared with libaio.
> 
> Great! Any chance I can get you to re-post the patches against the
> current tree?
> 
Yes, we'll do it later.

Thanks,
Joseph