Re: [PATCH v11 18/23] x86/resctrl: Report "Unassigned" for MBM events in mbm_cntr_assign mode

[Reinette Chatre]

Hi Babu,

On 1/22/25 12:20 PM, Babu Moger wrote:
> In mbm_cntr_assign mode, the hardware counter should be assigned to read
> the MBM events.
> 
> Report 'Unassigned' in case the user attempts to read the events without
> assigning the counter.
> 
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---

> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
> index 99cae75559b0..072b15550ff7 100644
> --- a/Documentation/arch/x86/resctrl.rst
> +++ b/Documentation/arch/x86/resctrl.rst
> @@ -431,6 +431,16 @@ When monitoring is enabled all MON groups will also contain:
>  	for the L3 cache they occupy). These are named "mon_sub_L3_YY"
>  	where "YY" is the node number.
>  
> +	When supported the mbm_cntr_assign mode allows users to assign a

Same comment as previous version.

> +	counter to mon_hw_id, event pair enabling bandwidth monitoring for
> +	as long as the counter remains assigned. The hardware will continue
> +	tracking the assigned mon_hw_id until the user manually unassigns
> +	it, ensuring that counters are not reset during this period. With
> +	a limited number of counters, the system may run out of assignable
> +	counters. In that case, MBM event counters will return 'Unassigned'
> +	when the event is read. Users must manually assign a counter to read
> +	the events.
> +
>  "mon_hw_id":
>  	Available only with debug option. The identifier used by hardware
>  	for the monitor group. On x86 this is the RMID.

Reinette