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

Reinette Chatre
2024-05-03T21:15:15Z

Hi Peter,

On 5/3/2024 2:00 PM, Peter Newman wrote:
> Hi Babu,
>
> On Fri, May 3, 2024 at 1:44 PM Moger, Babu <bmoger@amd.com> wrote:
>>
>> Hi Peter,
>>
>> On 5/2/2024 7:57 PM, Peter Newman wrote:
>>> Hi Reinette,
>>>
>>> On Thu, May 2, 2024 at 4:21 PM Reinette Chatre
>>>> I do think ABMC should be enabled by default when available and it looks
>>>> to be what this series aims to do [1]. The way I reason about this is
>>>> that legacy user space gets more reliable monitoring behavior without
>>>> needing to change behavior.
>>>
>>> I don't like that for a monitor assignment-aware user, following the
>>> creation of new monitoring groups, there will be less monitors
>>> available for assignment. If the user wants precise control over where
>>> monitors are allocated, they would need to manually unassign the
>>> automatically-assigned monitor after creating new groups.
>>>
>>> It's an annoyance, but I'm not sure if it would break any realistic
>>> usage model. Maybe if the monitoring agent operates independently of
>>
>> Yes. Its annoyance.
>>
>> But if you think about it, normal users don't create too many groups.
>> They wont have to worry about assign/unassign headache if we enable
>> monitor assignment automatically. Also there is pqos tool which uses
>> this interface. It does not have to know about assign/unassign stuff.
>
> Thinking about this again, I don't think it's much of a concern
> because the automatic assignment on mongroup creation behavior can be
> trivially disabled using a boolean flag.

This could be a config option.

Reinette