Re: [RFC PATCH v3 00/17] x86/resctrl : Support AMD Assignable Bandwidth Monitoring Counters (ABMC)

Moger, Babu
2024-05-08T23:29:31Z

Hi Reinette,

On 5/8/24 15:41, Reinette Chatre wrote:
> Hi Babu,
>
> On 5/8/2024 1:07 PM, Moger, Babu wrote:
>> Hi Reinette,
>>
>> On 5/7/24 15:26, Reinette Chatre wrote:
>>> Hi Babu,
>>>
>>> On 5/6/2024 10:18 AM, Moger, Babu wrote:
>>>> On 5/3/24 18:24, Reinette Chatre wrote:
>>>>> On 3/28/2024 6:06 PM, Babu Moger wrote:
>>>>>
>>>>>> a. Check if ABMC support is available
>>>>>> #mount -t resctrl resctrl /sys/fs/resctrl/
>>>>>>
>>>>>> #cat /sys/fs/resctrl/info/L3_MON/mbm_assign
>>>>>> [abmc]
>>>>>> legacy_mbm
>>>>>>
>>>>>> Linux kernel detected ABMC feature and it is enabled.
>>>>>
>>>>> Please note that this adds the "abmc" feature to the resctrl
>>>>> *filesystem* that supports more architectures than just AMD. Calling the
>>>>> resctrl filesystem feature "abmc" means that (a) AMD needs to be ok with
>>>>> other architectures calling their features that are
>>>>> similar-but-maybe-not-identical-to-AMD-ABMC "abmc", or (b) this needs
>>>>> a new generic name.
>>>>
>>>> It should not a problem if other architecture calling abmc for similar
>>>> feature. But generic name is always better if there is a suggestion.
>>>
>>> "should not a problem" does not instill confidence that AMD is
>>> actually ok with this.
>>
>> The feature "ABMC" has been used in the public document already to refer
>> this feature.
>> https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/programmer-references/24594.pdf
>
> It is clear to me that Assignable Bandwidth Monitoring Counters (ABMC) is the
> name of the AMD feature. The question is whether users can use the
> same name to interact with "similar but maybe not identical" features from other
> architectures, which is what this series enables.
>
>> If there comes a conflict then we can change it to amd_abmc. Didn't see
>> any conflict at this pint.
>
> How do you envision this? The resctrl filesystem interface is intended to be
> architecture neutral so it is not obvious to me how "amd_abmc" is expected
> to look? Why would it be necessary to have different architecture specific names
> for a similar feature from different architectures that users interact with in
> the same way? Sounds to me as though this just needs a new non-AMD marketing name.

I think I misunderstood it.
It is not a concern to have a same name("abmc") for similar feature across
the architectures.

ABMC is also kind of generic. I am open to other generic suggestions. I
think we should have "assign" and "monitor" words in them.
--
Thanks
Babu Moger