Re: [RFC V4 1/6] blk: prepare to make blk-rq-qos pluggable and modular

[Wang Jianchao]

On 2022/2/23 1:19 上午, Tejun Heo wrote:
> Hello,
> 
> On Thu, Feb 17, 2022 at 11:13:44AM +0800, Wang Jianchao (Kuaishou) wrote:
>> (3) Add /sys/block/x/queue/qos
>>     We can use '+name' or "-name" to open or close the blk-rq-qos
>>     policy.
> 
> I don't understand why we're modularizing rq-qos in this non-standard way
> instead of modprobing to enable a policy and rmmoding to disable. Why are we
> building in qos names into the kernel and adding an extra module handling
> interface?

Hi Tejun

We just want to provide the flexibility for the user to open/close a policy
per device. If we need to the policy on a device, we needn't to waste cpu
cycles and memory for it.

Thanks
Jianchao