Re: [PATCH v18 3/8] numa: Extend CLI to provide memory side cache information

[Markus Armbruster <armbru@redhat.com>]

Tao Xu <tao3.xu@intel.com> writes:

> From: Liu Jingqi <jingqi.liu@intel.com>
>
> Add -numa hmat-cache option to provide Memory Side Cache Information.
> These memory attributes help to build Memory Side Cache Information
> Structure(s) in ACPI Heterogeneous Memory Attribute Table (HMAT).

Please mention this requires -machine hmat=on.

> Reviewed-by: Igor Mammedov <imammedo@redhat.com>
> Reviewed-by: Daniel Black <daniel@linux.ibm.com>
> Signed-off-by: Liu Jingqi <jingqi.liu@intel.com>
> Signed-off-by: Tao Xu <tao3.xu@intel.com>
[...]
> diff --git a/qapi/machine.json b/qapi/machine.json
> index c741649d7b..3d0ba226a9 100644
> --- a/qapi/machine.json
> +++ b/qapi/machine.json
> @@ -428,10 +428,12 @@
>  #
>  # @hmat-lb: memory latency and bandwidth information (Since: 5.0)
>  #
> +# @hmat-cache: memory side cache information (Since: 5.0)
> +#
>  # Since: 2.1
>  ##
>  { 'enum': 'NumaOptionsType',
> -  'data': [ 'node', 'dist', 'cpu', 'hmat-lb' ] }
> +  'data': [ 'node', 'dist', 'cpu', 'hmat-lb', 'hmat-cache' ] }
>  
>  ##
>  # @NumaOptions:
> @@ -447,7 +449,8 @@
>      'node': 'NumaNodeOptions',
>      'dist': 'NumaDistOptions',
>      'cpu': 'NumaCpuOptions',
> -    'hmat-lb': 'NumaHmatLBOptions' }}
> +    'hmat-lb': 'NumaHmatLBOptions',
> +    'hmat-cache': 'NumaHmatCacheOptions' }}
>  
>  ##
>  # @NumaNodeOptions:
> @@ -647,6 +650,77 @@
>      '*latency': 'uint64',
>      '*bandwidth': 'size' }}
>  
> +##
> +# @HmatCacheAssociativity:
> +#
> +# Cache associativity in the Memory Side Cache
> +# Information Structure of HMAT
> +#
> +# For more information of @HmatCacheAssociativity see
> +# the chapter 5.2.27.5: Table 5-147 of ACPI 6.3 spec.

  # Cache associativity in the Memory Side Cache Information Structure
  # of HMAT
  #
  # For more information of @HmatCacheAssociativity, see chapter
  # 5.2.27.5: Table 5-147 of ACPI 6.3 spec.

> +#
> +# @none: None

What does cache associativity @none mean?  A none-associative cache?  I
guess it makes sense to people familiar with the ACPI spec...

> +#
> +# @direct: Direct Mapped
> +#
> +# @complex: Complex Cache Indexing (implementation specific)
> +#
> +# Since: 5.0
> +##
> +{ 'enum': 'HmatCacheAssociativity',
> +  'data': [ 'none', 'direct', 'complex' ] }
> +
> +##
> +# @HmatCacheWritePolicy:
> +#
> +# Cache write policy in the Memory Side Cache
> +# Information Structure of HMAT
> +#
> +# For more information of @HmatCacheWritePolicy see
> +# the chapter 5.2.27.5: Table 5-147: Field "Cache Attributes" of ACPI 6.3 spec.

Break lines around column 70, please.

> +#
> +# @none: None

What does cache write policy @none mean?

> +#
> +# @write-back: Write Back (WB)
> +#
> +# @write-through: Write Through (WT)
> +#
> +# Since: 5.0
> +##
> +{ 'enum': 'HmatCacheWritePolicy',
> +  'data': [ 'none', 'write-back', 'write-through' ] }
> +
> +##
> +# @NumaHmatCacheOptions:
> +#
> +# Set the memory side cache information for a given memory domain.
> +#
> +# For more information of @NumaHmatCacheOptions see
> +# the chapter 5.2.27.5: Table 5-147: Field "Cache Attributes" of ACPI 6.3 spec.
> +#
> +# @node-id: the memory proximity domain to which the memory belongs.
> +#
> +# @size: the size of memory side cache in bytes.
> +#
> +# @level: the cache level described in this structure.
> +#
> +# @assoc: the cache associativity, none/direct-mapped/complex(complex cache indexing).
> +#
> +# @policy: the write policy, none/write-back/write-through.
> +#
> +# @line: the cache Line size in bytes.
> +#
> +# Since: 5.0
> +##
> +{ 'struct': 'NumaHmatCacheOptions',
> +  'data': {
> +   'node-id': 'uint32',

Ignorant question: you use 'uint16' for other "proximity domains".  Is
'uint32' intentional here?

> +   'size': 'size',
> +   'level': 'uint8',
> +   'assoc': 'HmatCacheAssociativity',
> +   'policy': 'HmatCacheWritePolicy',
> +   'line': 'uint16' }}
> +
>  ##
>  # @HostMemPolicy:
>  #
[...]