linux-kernel - RE: [PATCH v8 08/25] x86/resctrl: Introduce interface to display number of monitoring counters

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Message-ID: <SJ1PR11MB6083DC9EA6D323356E957A87FC4E2@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date: Thu, 24 Oct 2024 17:37:37 +0000
From: "Luck, Tony" <tony.luck@...el.com>
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Subject: RE: [PATCH v8 08/25] x86/resctrl: Introduce interface to display
 number of monitoring counters

> >> Since you seem to want to keep the flexibility for a possible future
> >> where per-domain is needed. The "available_mbm_cntrs" file
> >> suggested in another thread would need to list available counters
> >> on each domain to avoid ABI problems should that future arrive.
> >>
> >> $ cat num_mbm_counters
> >> 32
> >>
> >> $ cat available_mbm_cntrs
> >> 0=12;1=9
> >
> > Good point.
> >
>
> Working on this now. Wanted to confirm if we really need domain specific
> information?
>
> To me, it does not seem necessary for the user. User cannot make any
> decisions based on this information.
>
> All user wants to know is if there are global counters available.
>
> $ cat num_mbm_counters
> 32
>
> $ cat available_mbm_cntrs
> 15

This approach paints resctrl into an ABI corner where it can't later
update resctrl to track counters per-domain. Maybe you'll never want to do that,
but some other architecture might want to have that flexibility.

-Tony