Re: [PATCH v5 2/2] x86,fs/resctrl: Keep mbm_assign_mode in default mode at boot

[Babu Moger <babu.moger@amd.com>]

Hi Reinette,

On 10/27/26 11:36, Reinette Chatre wrote:
> Hi Babu,
> 
> On 10/27/26 7:48 AM, Babu Moger wrote:
>> On 10/26/26 19:15, Reinette Chatre wrote:
>>> On 10/21/26 4:58 PM, Babu Moger wrote:
> 
> ...
> 
>>>
>>>> +  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
>>>> +  [default]
>>>> +  mbm_event
>>>> +
>>>> +The "default" mode is enabled. "mbm_event" is supported but not enabled.
>>>>    +b. Enable "mbm_event" mode. Switching the mbm_assign_mode may
>>>> +reset all the MBM counters (and thus all MBM events) of all the resctrl groups.
>>>> +::
>>>> +
>>>> +  # echo "mbm_event" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
>>>>      # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
>>>>      [mbm_event]
>>>>      default
>>>>    
>>>
>>> The above changes could be merged together under a single step "a" that
>>> will significantly reduce the churn when considering this is a stable patch.
>>
>> Yes. We can. But because of auto assign is not enabled on mode switch, we still have to touch few steps. Your choice.
> 
> Understood. The benefit here is that the patch will only change actual information.
> 
> Specifically, changes like the two below that just updates the letter
> associated with the step:
> 
>>>> -b. Check how many assignable counters are supported.
>>>> +c. Check how many assignable counters are supported.
>>>>    ::
>>>>        # cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs
>>>>      0=32;1=32

Yea. This will be dropped.>
> and
> 
>>>>    -c. Check how many assignable counters are available for assignment in each domain.
>>>> +d. Check how many assignable counters are available for assignment in each domain.
>>>>    ::
> 
> will be dropped from the patch. They distract from the core change and do not
> seem appropriate for a patch headed to stable.

Actually, the step (d) will be partially dropped as assignable counters 
changed from 30 to 32 without auto-assignment.

   # cat /sys/fs/resctrl/info/L3_MON/available_mbm_cntrs
-  0=30;1=30
+  0=32;1=32


Will send the updated series later this week.

Also, noticed a minor typo:

-  # cat /sys/fs/resctrl/mbm_L3_assignment
+  # cat /sys/fs/resctrl/mbm_L3_assignments


Thanks
Babu