Question on the hardware dispatch queue in blk-mq and NVMe submission queue

[Junjie Qian]

Hi all, 

I have one question (in latest kernel, 4.1.0) regarding the hardware dispatch queue in blk-mq and the submission queue in NVMe, that are these two queues the same one in the implementation? 

In another word, one IO (to SSD connected with NVMe) is issued from CPU, goes to the per-core software queue, then to hardware dispatch queue, what is next? The submission queue in NVMe or the device? 

Thanks! 
Best 
Junjie