Re: [PATCH v2 1/3] scsi: ufs: core: Introduce mcq ops to config cqid

[Bart Van Assche]

On 5/30/23 18:54, Stanley Chu wrote:
> In addition, some benchmark data shows that the performance can be
> improved by using fewer CQs to aggregate the interrupt handling of
> completion requests.

What has been measured? IOPS only or both IOPS and latency?

How big is the difference? A few percent or more?

For which number of SQs and which number of CQs has performance data 
been measured?

Would the following work instead of introducing a new vop?
- Introduce a new capability flag, e.g. UFSHCD_CAP_SINGLE_CQ.
- Set that flag from inside ufs_mtk_init().
- Modify the UFS core driver such that the number of completion queues
  depends on the UFSHCD_CAP_SINGLE_CQ flag.

> Therefore, we would like to introduce a vop to allow the host to
> configure it accordingly.

We do not accept new vops upstream without a user. Where is the 
implementation of the new .config_cqid() callback?

Thanks,

Bart.