Re: [PATCH 1/2] x86/resctrl, Documentation: Keep mbm_assign_mode "default" on boot

[Borislav Petkov]

On Fri, Jul 31, 2026 at 07:59:46AM -0700, Reinette Chatre wrote:
> The underlying implementations appear to be different between AMD and Intel.
> On Intel side only the RMIDs (not separate hardware counters) need to be
> considered.  resctrl supports this RMID limit by placing a limit on how many
> monitoring groups the user can create.

Sounds to me like the AMD side should do this too, no, if it doesn't already?

I mean, it is kinda natural behavior to track counter occupancy and deny the
allocation of new ones if there are none free...

> The Intel/RDT spec does leave room for this to occur but a return of
> "Unavailable" when reading a monitoring event is not encountered on current
> Intel hardware.

Why not? Because nothing's reaching that limit or?

> The user can always expect a value when reading a monitoring event (on
> current hardware).

How does that work when you exhaust the counters? Or it does switch between
them quickly so that there's always *something* that counts?

Hmmm.

-- 
Regards/Gruss,
    Boris.

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