Re: [PATCH v4] scsi: ufs: core: Add trace event for MCQ

[Ziqi Chen]

On 3/7/2023 11:47 PM, Bart Van Assche wrote:
> On 3/6/23 21:53, Ziqi Chen wrote:
> > You are right,  users may hate it if the trace events for legacy mode 
> > and MCQ mode are different. But if I merge them into one event, it 
> > will print much invalid information as we can not add if-else into 
> > TP_printk().
> >
> > (For example:  in SDB legacy mode, you can see such invalid prints " 
> > hqid = 0 , sqt= 0, cqh=0, cqt = 0")
> >
> > Users may hate these invalid information.
> >
> > Anyway, I have made new version that merge 2 mode into one event, but 
> > are you sure we really need to use this way? if yes , I can push new 
> > version here.
> >
> > Or, could you give some suggestions if you have better way.
> >
> > Below is a piece of new version code , you can preview.
> >
> >      TP_fast_assign(
> >          __assign_str(dev_name, dev_name);
> >          __entry->str_t = str_t;
> >          __entry->tag = tag;
> >          __entry->doorbell = doorbell;
> >          __entry->hwq_id = hwq? hwq->id: 0;
> >          __entry->sq_tail = hwq? hwq->sq_tail_slot: 0;
> >          __entry->cq_head = hwq? hwq->cq_head_slot: 0;
> >          __entry->cq_tail = hwq? hwq->cq_tail_slot: 0;
> >          __entry->transfer_len = transfer_len;
> >          __entry->lba = lba;
> >          __entry->intr = intr;
> >          __entry->opcode = opcode;
> >          __entry->group_id = group_id;
> >      ),
> >
> >      TP_printk(
> >          "%s: %s: tag: %u, DB: 0x%x, size: %d, IS: %u, LBA: %llu, 
> > opcode: 0x%x (%s),"
> >          "group_id: 0x%x, hqid: %d, sqt: %d, cqh: %d, cqt: %d",
> >          show_ufs_cmd_trace_str(__entry->str_t), __get_str(dev_name), 
> > __entry->tag,
> >          __entry->doorbell, __entry->transfer_len, __entry->intr, 
> > __entry->lba,
> >          (u32)__entry->opcode, str_opcode(__entry->opcode), 
> > (u32)__entry->group_id,
> >          __entry->hwq_id,__entry->sq_tail, __entry->cq_head, 
> > __entry->cq_tail
> >      )
>
> Hi Ziqi,
>
> Please reply below the original e-mail instead of above. This is 
> expected on Linux kernel mailing lists.
>
> Regarding your question: I propose to leave out the sq_tail, cq_head and 
> cq_tail information. That information may be useful for hardware 
> developers but is not useful for other users of the Linux kernel. So the 
> only piece of information that is left that is MCQ-specific is the 
> hardware queue index. I expect that users will be fine to see that 
> information in trace events.
>
> How about reporting hardware queue index -1 for legacy mode instead of 
> 0? That will allow users to tell the difference between legacy mode and 
> MCQ mode from the trace events.
>
> Thanks,
>
> Bart.

Hi Bart,

Thanks for you suggestion. But the member hwq->id is an Unsigned 
integer. if you want to identify SDB mode and MCQ mode,  using "0" is 
enough, Or how about add string such as below?

ufshcd_command: MCQ: complete_rsp: 1d84000.ufshc: tag: 14, DB: 0x0, 
size: 32768, IS: 0, LBA: 5979448,opcode: 0x2a (WRITE_10),group_id: 0x0, 
hqid: 2

Ziqi
>