Re: [PATCH 1/5] scsi: hisi_sas: Add host_tagset_enable module param for v3 hw

[yangxingui <yangxingui@huawei.com>]

On 2025/3/31 16:40, Niklas Cassel wrote:
> Hello Xingui,
> 
> On Sat, Mar 29, 2025 at 05:49:47PM +0800, yangxingui wrote:
>> Hi，John
>>
>> On 2025/3/29 16:50, John Garry wrote:
>>> On 29/03/2025 07:32, Yihang Li wrote:
>>>
>>> +
>>>
>>>> From: Xingui Yang<yangxingui@huawei.com>
>>>>
>>>> After driver exposes all HW queues and application submits IO to multiple
>>>> queues in parallel, if NCQ and non-NCQ commands are mixed to sata disk,
>>>> ata_qc_defer() causes non-NCQ commands to be requeued and possibly
>>>> repeated
>>>> forever.
>>>
>>> I don't think that it is a good idea to mask out bugs with module
>>> parameters.
>>>
>>> Was this the same libata/libsas issue reported some time ago?
>>
>> Yeah，related to this issue: https://lore.kernel.org/linux-block/eef1e927-c9b2-c61d-7f48-92e65d8b0418@huawei.com/
>>
>> And, Niklas tried to help fix this problem:
>> https://lore.kernel.org/linux-scsi/ZynmfyDA9R-lrW71@ryzen/
>>
>> Considering that there is no formal solution yet. And our users rarely use
>> SATA disks and SAS disks together on a single machine. For this reason, they
>> can flexibly turn off the exposure of multiple queues in the scenario of
>> using only SATA disks. In addition, it is also convenient to conduct
>> performance comparison tests to expose multiple hardware queues and single
>> queues.
> 
> The solution I sent is not good since it relies on EH.
> 
> One would need to come up with a better solution to fix libsas drivers,
> possibly a workqueue.
> 
> I think Damien is planning to add a workqueue submit path to libata,
> if so, perhaps we could base a better solution on top of that.

Thank you for your solution. As you said, we may need a better solution.

Thanks,
Xingui
.