Re: [RESEND PATCH v4 09/15] fs/resctrl: Introduce kmode_cpus/kmode_cpus_list per rdtgroup

[Babu Moger <babu.moger@amd.com>]

Hi Reinette,

On 8/13/26 13:19, Reinette Chatre wrote:
> Hi Babu,
> 
> On 8/13/26 10:57 AM, Babu Moger wrote:
>> Hi Reinette,
>>
>> On 8/10/26 22:20, Reinette Chatre wrote:
>>> Hi Babu,
>>>
>>> On 7/7/26 2:50 PM, Babu Moger wrote:
>>>> Kernel-mode resctrl policies allow kernel work to be associated with a
>>>> specific rdtgroup, optionally restricted to a subset of online CPUs.
>>>>
>>>> While user space can query the active kernel-mode policy and its associated
>>>> rdtgroup through info/kernel_mode, it currently lacks visibility into the
>>>> CPU scope of that binding.
>>>>
>>>> Introduce read-only kmode_cpus and kmode_cpus_list files for each rdtgroup.
>>>
>>> I think it will be easier to follow if this is deferred to not create these
>>> files in all resource groups by default. Instead, at the time they are
>>> created it should be obvious that they will only be visible in resource group
>>> associated with the active kernel mode.
>>
>> I am not clear on this comment. Do you mean create these files when user associates the group to kernel mode? (during rdtgroup_config_kmode)
> 
> No. As this changelog states it creates these files in all resource groups. This
> is a confusing thing to do at this point in the series since these files are not
> expected to be present/visible in all resource groups, only in a resource group that
> is assigned to the "global" kernel mode. This commit mentions nothing about this
> usage and thus from reader perspective does not seem like the right thing to do here.

Ok. Got it. Commit message is not clear.

> 
>>
>> Also, you mentioned about rftype::create_hidden in
>> https://lore.kernel.org/lkml/0126a5e5-48cf-416f-a21b-c231a703c18b@intel.com/
>>
>> Can you please clarify on this?
> 
> resctrl has centralized functions to create files. For example, rdtgroup_add_file()
> that takes as parameter the properties of the file, struct rftype. With a new
> property, for example rftype::create_hidden the file's default visibility can be
> set _at the time it is created_. This simplifies the code by not needing to sprinkle
> changes to these files' visibility after the fact at the various places files are created.
> 
> One patch can add capability to resctrl to have a file property indicating that the
> file should essentially be created with KERNFS_HIDDEN set.
> 
> This patch can then follow by using the capability to create the kmode_cpus and
> kmode_cpus_list files in all resource groups and it will be clear that the files
> are not exposed to user space by default.

Soundd good. We can do that.
Thanks
Babu