Re: [RFC v2] arm,x86,fs/resctrl: Generic schema description Proof of Concept

[Reinette Chatre]

Hi Chenyu,

On 8/18/26 9:02 AM, Chen Yu wrote:
> On Thu, Aug 13, 2026 at 08:19:38AM -0700, Reinette Chatre wrote:
>> On 8/13/26 6:59 AM, Chen Yu wrote:
>>> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
>>> index cac4b3293cef..ab7d3fa3f337 100644
>>> --- a/fs/resctrl/rdtgroup.c
>>> +++ b/fs/resctrl/rdtgroup.c
>>> @@ -124,7 +124,7 @@ void rdt_staged_configs_clear(void)
>>>                         if (list_empty(&ctrl->emulated_by))
>>>                                 continue;
>>>                         list_for_each_entry(em_ctrl, &ctrl->emulated_by, entry) {
>>> -                               list_for_each_entry_rcu(dom, &ctrl->domains, hdr.list, lockdep_is_cpus_held())
>>> +                               list_for_each_entry_rcu(dom, &em_ctrl->domains, hdr.list, lockdep_is_cpus_held())
>>>                                         memset(dom->staged_config, 0, sizeof(dom->staged_config));
>>>                         }
>>>                 }
>> Thank you very much. Squashed and available in branch resctrl/controls_rfc_v2.2
>>
> 
> :) Another minor one
> otherwise a schemata write on Haswell would only update rdt_hw_ctrl_domain::ctrl_val[]
> and never reach MSR_IA32_L3_CBM_BASE.
> 
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -175,6 +175,10 @@ static inline void cache_alloc_hsw_probe(void)
>  	hw_ctrl->r_ctrl.bitmap.cbm_len = 20;
>  	hw_ctrl->r_ctrl.bitmap.shareable_bits = 0xc0000;
>  	hw_ctrl->r_ctrl.bitmap.min_cbm_bits = 2;
> +
> +	hw_ctrl->msr_base = MSR_IA32_L3_CBM_BASE;
> +	hw_ctrl->hw_update = cat_wrmsr;
> +

Thank you very much.

This seems to be a patch that requires additional changes that are not
in the PoC. I squashed this after a change to use msr_update instead of
hw_update, now available in resctrl/controls_rfc_v2.4.

We could do the rename of these function pointers as part of the PoC but
that would also require adjustments to the parameters that would need more
insight into the future requirements. 

Reinette