Hi Babu,
On 10/27/2022 8:30 AM, Moger, Babu wrote:
> On 10/26/22 15:23, Reinette Chatre wrote:
>> On 10/26/2022 12:07 PM, Moger, Babu wrote:
>>> On 10/25/22 18:43, Reinette Chatre wrote:
>>>> On 10/17/2022 3:26 PM, Babu Moger wrote:
>>>>
>>>> ...
>>>>
>>>>> @@ -2845,7 +2846,8 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
>>>>>
>>>>> list_for_each_entry(s, &resctrl_schema_all, list) {
>>>>> r = s->res;
>>>>> - if (r->rid == RDT_RESOURCE_MBA) {
>>>>> + if (r->rid == RDT_RESOURCE_MBA ||
>>>>> + r->rid == RDT_RESOURCE_SMBA) {
>>>>> rdtgroup_init_mba(r, rdtgrp->closid);
>>>>> if (is_mba_sc(r))
>>>>> continue;
>>>> The above hunk and the ones that follow are unexpected.
>>> I am thinking the above check is required, It is updating the
>>> staged_config with default values. Right now, the default value for SMBA
>>> is same as MBA default value. So, I used this code to initialize.
>>>
>>> Did I miss something?
>> As I described in the following comments my concern is related to all the
>> software controller code still executing for SMBA. Yes, in the above hunk
>> SMBA would need (some of) rdtgroup_init_mba() ... but note that it contains
>> software controller checks and in the above hunk its call is also followed
>> by another software controller check.
>>
>> The software controller is just applicable to MBA and these checks have been
>> isolated to the MBA resource. Using it for SMBA that does not support
>> software controller at all is making the code harder to follow and sets this
>> code up for future mistakes. I think it would make the code easier to understand
>> if this is made very clear that software controller is not applicable to SMBA at
>> all instead of repurposing these flows.
>
> Yes. Understood. How about this? I feel this is much more cleaner.
>
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index e5a48f05e787..d91a6a513681 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -2845,16 +2845,18 @@ static int rdtgroup_init_alloc(struct rdtgroup
> *rdtgrp)
>
> list_for_each_entry(s, &resctrl_schema_all, list) {
> r = s->res;
> - if (r->rid == RDT_RESOURCE_MBA) {
> + if (r->rid == RDT_RESOURCE_MBA ||
> + r->rid == RDT_RESOURCE_SMBA) {
> rdtgroup_init_mba(r, rdtgrp->closid);
> - if (is_mba_sc(r))
> - continue;
> } else {
> ret = rdtgroup_init_cat(s, rdtgrp->closid);
> if (ret < 0)
> return ret;
> }
>
> + if (is_mba_sc(r))
> + continue;
> +
> ret = resctrl_arch_update_domains(r, rdtgrp->closid);
> if (ret < 0) {
> rdt_last_cmd_puts("Failed to initialize
> allocations\n");
>
I do not see how that move changes what is run in the SMBA case and it ignores the
is_mba_sc() call within rdtgroup_init_mba(). How about making is_mba_sc() more
robust in support of your original snippet?
Something like:
bool is_mba_sc(struct rdt_resource *r)
{
if (!r)
return rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl.membw.mba_sc;
if (r->rid != RDT_RESOURCE_MBA)
return false;
return r->membw.mba_sc;
}
Reinette
