Hello,

On Wed, Jul 28, 2021 at 10:33:20AM +0800, brookxu wrote:

If we do this, I think we will encounter some problems, as follows:
1. blk-throttle is now at the top of the IO stack. Changing the position of the throttle hook
   will make this mechanism invalid for some devices.
2. We may also need to add a new hook to handle back-merge, otherwise I think the isolation
   effect will be worse in the sequential IO scene.
3. Since bio has entered the IO stack, if it is suspended and resubmitted by blk-throttle,
   then there is an IO stack reentry problem, which I think may cause many small problems.

Yeah, you're right. I don't think it's worth rocking the boat with
blk-throtl at this point. An extra callback it is then.

Thanks.

-- 
tejun