Re: [RFC V4 0/6] blk: make blk-rq-qos policies pluggable and modular

[Wang Jianchao]

On 2022/2/17 11:21 上午, Jens Axboe wrote:
> On 2/16/22 8:13 PM, Wang Jianchao (Kuaishou) wrote:
>> Hi Jens
>>
>> blk-rq-qos is a standalone framework out of io-sched and can be used to
>> control or observe the IO progress in block-layer with hooks. blk-rq-qos
>> is a great design but right now, it is totally fixed and built-in and shut
>> out peoples who want to use it with external module.
>>
>> This patchset attempts to make blk-rq-qos framework pluggable and modular.
>> Then we can update the blk-rq-qos policy module w/o stopping the IO workload.
>> And it is more convenient to introduce new policy on old machines w/o udgrade
>> kernel. And we can close all of the blk-rq-qos policy if we needn't any of
>> them. At the moment, the request_queue.rqos list is empty, we needn't to
>> waste cpu cyles on them.
> 
> I like this patchset, would be a lot more convenient and helps
> efficiency.
> 
> What kind of testing have you done on it?
> 
I have run blktests against this patchset in a VM machine along with a new test
case for switching rqos policies while running IO. 

https://marc.info/?l=linux-block&m=164506848620632&w=2

And also there is a bit different version running on v4.18 with more tests

Thanks
Jianchao