Re: [RFC PATCH v3 17/17] x86/resctrl: Introduce interface to modify assignment states of the groups

Moger, Babu
2024-04-17T22:52:28Z

Hi Peter,

On 4/17/2024 3:56 PM, Peter Newman wrote:
> Hi Babu,
>
> On Wed, Apr 17, 2024 at 12:39 PM Moger, Babu <babu.moger@amd.com> wrote:
>> On 4/17/24 12:45, Peter Newman wrote:
>>> On Thu, Mar 28, 2024 at 6:10 PM Babu Moger <babu.moger@amd.com> wrote:
>>>> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
>>>> index 2d96565501ab..64ec70637c66 100644
>>>> --- a/Documentation/arch/x86/resctrl.rst
>>>> +++ b/Documentation/arch/x86/resctrl.rst
>>>> @@ -328,6 +328,77 @@ with the following files:
>>>> None of events are assigned on this mon group. This is a child
>>>> monitor group of the non default control mon group.
>>>>
>>>> + Assignment state can be updated by writing to this interface.
>>>> +
>>>> + NOTE: Assignment on one domain applied on all the domains. User can
>>>> + pass one valid domain and assignment will be updated on all the
>>>> + available domains.
>>> How would different assignments to different domains work? If the
>>> allocations are global, then the allocated monitor ID is available to
>>> all domains whether they use it or not.
>> That is correct.
>> [A] Hardware counters(max 2 per group) are allocated at the group level.
>> So, those counters are available to all the domains on that group. I will
>> maintain a bitmap at the domain level. The bitmap will be set on the
>> domains where assignment is applied and IPIs are sent. IPIs will not be
>> sent to other domains.
> Unless the monitor allocation is scoped at the domain level, I don't
> see much point in implementing the per-domain parsing today, as the
> only benefit is avoiding IPIs to domains whose counters you don't plan
> to read.

In that case lets remove the domain specific assignments. We can avoid
some code complexity.

thanks

Babu