Re: [PATCH 8/8] qemu-options: Add the description of smp-cache object

[Markus Armbruster <armbru@redhat.com>]

Zhao Liu <zhao1.liu@intel.com> writes:

> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>

This patch is just documentation.  The code got added in some previous
patch.  Would it make sense to squash this patch into that previous
patch?

> ---
> Changes since RFC v2:
>  * Rewrote the document of smp-cache object.
>
> Changes since RFC v1:
>  * Use "*_cache=topo_level" as -smp example as the original "level"
>    term for a cache has a totally different meaning. (Jonathan)
> ---
>  qemu-options.hx | 58 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 58 insertions(+)
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 8ca7f34ef0c8..4b84f4508a6e 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -159,6 +159,15 @@ SRST
>          ::
>  
>              -machine cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.targets.1=cxl.1,cxl-fmw.0.size=128G,cxl-fmw.0.interleave-granularity=512
> +
> +    ``smp-cache='id'``
> +        Allows to configure cache property (now only the cache topology level).
> +
> +        For example:
> +        ::
> +
> +            -object '{"qom-type":"smp-cache","id":"cache","caches":[{"name":"l1d","topo":"core"},{"name":"l1i","topo":"core"},{"name":"l2","topo":"module"},{"name":"l3","topo":"die"}]}'
> +            -machine smp-cache=cache
>  ERST
>  
>  DEF("M", HAS_ARG, QEMU_OPTION_M,
> @@ -5871,6 +5880,55 @@ SRST
>          ::
>  
>              (qemu) qom-set /objects/iothread1 poll-max-ns 100000
> +
> +    ``-object '{"qom-type":"smp-cache","id":id,"caches":[{"name":cache_name,"topo":cache_topo}]}'``
> +        Create an smp-cache object that configures machine's cache
> +        property. Currently, cache property only include cache topology
> +        level.
> +
> +        This option must be written in JSON format to support JSON list.

Why?

> +
> +        The ``caches`` parameter accepts a list of cache property in JSON
> +        format.
> +
> +        A list element requires the cache name to be specified in the
> +        ``name`` parameter (currently ``l1d``, ``l1i``, ``l2`` and ``l3``
> +        are supported). ``topo`` parameter accepts CPU topology levels
> +        including ``thread``, ``core``, ``module``, ``cluster``, ``die``,
> +        ``socket``, ``book``, ``drawer`` and ``default``. The ``topo``
> +        parameter indicates CPUs winthin the same CPU topology container
> +        are sharing the same cache.
> +
> +        Some machines may have their own cache topology model, and this
> +        object may override the machine-specific cache topology setting
> +        by specifying smp-cache object in the -machine. When specifying
> +        the cache topology level of ``default``, it will honor the default
> +        machine-specific cache topology setting. For other topology levels,
> +        they will override the default setting.
> +
> +        An example list of caches to configure the cache model (l1d cache
> +        per core, l1i cache per core, l2 cache per module and l3 cache per
> +        socket) supported by PC machine might look like:
> +
> +        ::
> +
> +              {
> +                "caches": [
> +                   { "name": "l1d", "topo": "core" },
> +                   { "name": "l1i", "topo": "core" },
> +                   { "name": "l2", "topo": "module" },
> +                   { "name": "l3", "topo": "socket" },
> +                ]
> +              }
> +
> +        An example smp-cache object would look like:()
> +
> +        .. parsed-literal::
> +
> +             # |qemu_system| \\
> +                 ... \\
> +                 -object '{"qom-type":"smp-cache","id":id,"caches":[{"name":cache_name,"topo":cache_topo}]}' \\
> +                 ...
>  ERST