Re: [PATCH] scsi: ufs: mark HPB support as BROKEN

Martin K. Petersen
2021-10-27T16:16:36Z

Jens,

> It'd be feasible to have less reserved tags, you only need as many as
> you want to have these special commands inflight. Post that,
> returning BUSY and just retrying when a request completes should be
> fine. Hence I'd size the reserved tag pool appropriately depending on
> what kind of performance is expected out of this, with just 1 reserved
> tag being enough to give us the guarantees we need for forward
> progress.

Yep. Since this is labeled as a performance feature I do think it's
important to find the right balance between reserved and real tags.

> I think the plan forward is clear here then:
>
> 1) Revert the optimization that requires the use of cloned insert for
> 5.15.

Given that HPB developed over time, I am not sure how simple a revert
would be. And we only have a couple of days left before release. I
really want the smallest patch possible that either removes or disables
the 2.0 support.

--
Martin K. Petersen Oracle Linux Engineering