Re: Question about poll_multi_file

[Hao Xu <haoxu@linux.alibaba.com>]

在 2021/6/4 上午2:01, Jens Axboe 写道:
> On 6/3/21 6:53 AM, Hao Xu wrote:
>> Hi Jens,
>> I've a question about poll_multi_file in io_do_iopoll().
>> It keeps spinning in f_op->iopoll() if poll_multi_file is
>> true (and we're under the requested amount). But in my
>> understanding, reqs may be in different hardware queues
>> for blk-mq device even in this situation.
>> Should we consider the hardware queue number as well? Some
>> thing like below:
> 
> That looks reasonable to me - do you have any performance
> numbers to go with it?

Not very easy for me to construct a good case. I'm trying to
mock the below situation:
manully control uring reqs to go to 2 hardware queues, like:
    hw_queue0     hw_queue1
    heavy_req     simple_req
    heavy_req     simple_req
      ...            ...

heavy_req is some request that needs more time to complete,
while simple_req takes less time. And make the io_do_iopoll()
alway first spin on hw_queue0.
any ideas?

Thanks,
Hao
>