Re: [RFC PATCH 3/3] x86/resctrl: Display the RMID and COSID for resctrl groups

[Moger, Babu]

Hi Fenghua,

On 1/4/23 17:54, Yu, Fenghua wrote:
> Hi, Babu,
>
>>>> When a user creates a control or monitor group, the CLOSID or RMID
>>>> are not visible to the user. These are architecturally defined entities.
>>>> There is no harm in displaying these in resctrl groups. Sometimes it
>>>> can help to debug the issues.
>>> Although "no harm" to show them, it's not useful for generic user
>>> either and may cause confusion sometimes. CLOSID and RMID are supposed
>>> to be invisible to generic users.
>>>
>>> Maybe introduce a new resctrl mount option called "debug" and show the
>>> files and maybe other future debug info only in debug mode?
>> Actually, test team feels very strongly about this. Whenever there is some issue,
>> first question is what is the rmid or closid are you running on? We normally don't
>> have an answer for that.
>>
>> In my opinion, adding debug mode just for these two fields seems way overkill.
> Yes, they are useful for "test team" (quoted from your statement) and developers.
> Not for end users.
>
> A debug mode is useful not just for these two files. I'm working on another resctrl
> project where much more complex hardware info needs to be dumped for debug purpose
> only. It's obvious not to show it in generic use. It's more obvious to just show the info file in
> debug mode in my case.
>
> I think these CLOSID and RMID files and future debug files belong to a new debug mode.
> It would be better to introduce the debug mode now rather than later so that it can be extended
> easily in the future.
>
> Maybe we can enable debug mode in a separate debug mode patch:
> 1. Add RFTYPE_DEBUG as a new file type. Files with this flag are for debug purpose and only be visible in\
>     debug mode.
> 2. Add RFTYPE_INVISIBLE as a new file type. Files with this flag will be invisible/not be added in resctrl fs.
> 3. Add mount parameter "debug" so that ctx->debug=true if mount -o debug is given.
> 4. If ctx->debug is true, in rdt_enable_ctx(), go through RFTYPE_DEBUG files in res_common_files[] and mark
>     fflags with RFTYPE_INVISIBLE.
> 5. In rdtgroup_add_file(), if (rft->fflags & RFTYPE_INVISIBLE) return. So the debug files will be visible only
>     in debug mode.
>
> With the debug mode patch in place, it's simple to extend to any debug files:
> In your case, update this patch by just adding RFTYPE_DEBUG in fflags. Then the debug mode will work
> for this patch automatically.
> In my case or any future debug files, we just simply add RFTYPE_DEBUG in fflags and the debug mode will
> work automatically.
>
> Does it make sense?

Yes. Sure. The debug mode needs to be resctrl mount option. I will take a
look at this further to see what can be done.

Thanks

Babu