Re: [PATCH v2 07/24] x86/resctrl: Store the effective num_closid in the schema

Reinette Chatre
2021-03-31T21:39:57Z

Hi James,

On 3/12/2021 9:58 AM, James Morse wrote:
> The resctrl_schema struct holds properties that vary with the style of
> configuration that resctrl applies to a resource.
>
> There are already two values for the hardware's num_closid, depending on
> whether the architecture presents the L3 or L3CODE/L3DATA resources.
>
> As the way CDP changes the number of control groups that resctrl can create
> is part of the user-space interface, it should be managed by the filesystem

s/create is part of/create as part of/ ?

> parts of resctrl. This allows the architecture code to only describe the
> value the hardware supports.
>
> Add num_closid to resctrl_schema. This is the value seen by the filesystem,
> and when the CDP resources are merged, will be different to the value
> described by the arch code when CDP is enabled.
>
> These functions operate on the num_closid value that is exposed to
> user-space:
> rdtgroup_parse_resource()
> rdtgroup_schemata_show()
> rdt_num_closids_show()
> closid_init()
>
> These are changed to use the schema value instead.
>
> schemata_list_create() sets this value, and reaches into the architecture
> specific structure to get the value. This will eventually be replaced with
> a helper.
>
> Reviewed-by: Jamie Iles <jamie@nuviainc.com>
> Signed-off-by: James Morse <james.morse@arm.com>

...

> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index c6f749f54765..0ff10468940b 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -165,10 +165,12 @@ struct rdt_resource {
> * @list: Member of resctrl's schema list
> * @conf_type: Whether this entry is for code/data/both
> * @res: The rdt_resource for this entry
> + * @num_closid: Number of CLOSIDs available for this resource

It is not clear what "this resource" is. This description is essentially
the same as its copy found in rdt_hw_resource. Could you please improve
these descriptions to capture the differences between the two num_closid
values?

Thank you

Reinette