Hello,

On Tue, Jul 27, 2021 at 11:06:18AM +0800, brookxu wrote:

Make blk-throttle use rq-qos may be more elegant. But I found that there may be at least
one problem that is difficult to solve. blk-throttle supports separate throttle for read
and write IOs, which means that we cannot suspend tasks during throttle, but rq-qos
throttle IOs by suspending tasks.

Ah, right, I forgot about that.

We may be able to relocate the blk-throttle hooks to the rq-qos hooks. Since we may not
be able to replace the throttle hook, in this case, if we register a rq-qos to the system,
part of the blk-throttle hooks is in rq-qos and part hooks not, which feels a bit confusing.
In addition, we may need to implement more hooks, such as IO merge hook.

Would it be possible to just move the blk-throtl throttling hook right next
to the rq-qos hook so that it gets throttled after splitting?

Thanks.

-- 
tejun