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Also, sorry to come back late >>>>>> in the >>>>>> series. >>>>>> >>>>>> Looking at the series again, I see this approach adds lots of code. >>>>>> Look at this structure. >>>>>> >>>>>> >>>>>> @@ -187,10 +196,12 @@ struct rdt_resource { >>>>>>        bool            alloc_capable; >>>>>>        bool            mon_capable; >>>>>>        int            num_rmid; >>>>>> -    enum resctrl_scope    scope; >>>>>> +    enum resctrl_scope    ctrl_scope; >>>>>> +    enum resctrl_scope    mon_scope; >>>>>>        struct resctrl_cache    cache; >>>>>>        struct resctrl_membw    membw; >>>>>> -    struct list_head    domains; >>>>>> +    struct list_head    ctrl_domains; >>>>>> +    struct list_head    mon_domains; >>>>>>        char            *name; >>>>>>        int            data_width; >>>>>>        u32            default_ctrl; >>>>>> >>>>>> There are two scope fields. >>>>>> There are two domains fields. >>>>>> >>>>>> These are very confusing and very hard to maintain. Also, I am not >>>>>> sure if >>>>>> these fields are useful for anything other than SNC feature. This >>>>>> approach >>>>>> adds quite a bit of code for no specific advantage. >>>>>> >>>>>> Why don't we just split the RDT_RESOURCE_L3 resource >>>>>> into separate resources, one for control, one for monitoring. >>>>>> We already have "control" only resources (MBA, SMBA, L2). Lets >>>>>> create new >>>>>> "monitor" only resource. I feel it will be much cleaner approach. >>>>>> >>>>>> Tony has already tried that approach and showed that it is much >>>>>> simpler. >>>>>> >>>>>> v15-RFC : >>>>>> https://lore.kernel.org/lkml/20240130222034.37181-1-tony.luck@intel.com/ >>>>>> >>>>>> What do you think? >>>>>> >>>>> >>>>> Some highlights of my thoughts in response to that series, but the whole >>>>> thread >>>>> may be of interest to you: >>>>> https://lore.kernel.org/lkml/78c88c6d-2e8d-42d1-a6f2-1c5ac38fb258@intel.com/ >>>>> https://lore.kernel.org/lkml/59944211-d34a-4ba3-a1de-095822c0b3f0@intel.com/ >>>>> >>>> >>>> Went through the thread, in summary: >>>> >>>> The main concerns are related to duplication of code and data structures. >>>> >>>> The solutions are >>>> >>>> a) Split the domains. >>>> This is what this series is doing now. This creates members like >>>> ctrl_scope, mon_scope, ctrl_domains etc.. These fields are added to all >>>> the resources (MBA, SMBA and L2). Then there is additional domain header. >>>> >>>> >>>> b) Split the resource. >>>>    Split RDT_RESOURCE_L3 into two, one for "monitor" and one for >>>> "control". >>>>    There will be one domain structure for "monitor" and  one for >>>> "control" >>>> >>>> Both these approaches have code and data duplication. So, there is no >>>> difference that way. >>> >>> Could you please elaborate where code and data duplication of (a) is? >> >> We have ctrl_scope, mon_scope, ctrl_domains. mon_domains.  Only one >> resource, RDT_RESOURCE_L3 is going to use these fields. Rest of the >> resources don't need these fields. But these fields are part of all >> the resources. > > Correct. There are two new empty fields per resource that does > not support monitoring. Having the new mon_domains list results in > the benefit of eliminating monitoring fields from all the domains > forming part of resources that do not support monitoring. Providing > more details below but the additional pointer results in a significant > net reduction of unused fields. Having the new mon_scope field results > in the benefit to support SNC. > >> >> I am not too worried about the size of the patch.  But, I don't >> foresee these fields will be used anytime soon in these >> resources(MBA. L3. SMBA). Why add it now? In future we may have to >> cleanup all these anyways. > > This work does indeed go through the effort to _eliminate_ unused fields. > Note how all domains of all resources (whether they support monitoring or > not) currently have to carry a significant number of monitoring fields. > These can be found in both struct rdt_domain (*rmid_busy_llc, *mbm_total, > *mbm_local, mbm_over, cqm_limbo, mbm_work_cpu, cqm_work_cpu)  as > well as struct rdt_hw_domain (*arch_mbm_total, *arch_mbm_local). > > For a resource that does not support monitoring it is of course > unnecessary to carry all of this for _every_ domain instance and > after this series it no longer will. Yes. I see that. Thanks for the explanation. Lets go ahead with the series. This feature is been pending for a while. I will provide my comments for series. -- Thanks Babu Moger