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

From: Bart Van Assche
Date: Wed May 31 2023 - 08:50:09 EST

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?