Re: [RFC v2 1/7] hw/core: Make CPU topology enumeration arch-agnostic

Zhao Liu
2024-06-04T08:18:30Z

Hi Markus,

On Mon, Jun 03, 2024 at 02:25:36PM +0200, Markus Armbruster wrote:
> Date: Mon, 03 Jun 2024 14:25:36 +0200
> From: Markus Armbruster <armbru@redhat.com>
> Subject: Re: [RFC v2 1/7] hw/core: Make CPU topology enumeration
> arch-agnostic
>
> Zhao Liu <zhao1.liu@intel.com> writes:
>
> > Cache topology needs to be defined based on CPU topology levels. Thus,
> > define CPU topology enumeration in qapi/machine.json to make it generic
> > for all architectures.
> >
> > To match the general topology naming style, rename CPU_TOPO_LEVEL_SMT
> > and CPU_TOPO_LEVEL_PACKAGE to CPU_TOPO_LEVEL_THREAD and
> > CPU_TOPO_LEVEL_SOCKET.
> >
> > Also, enumerate additional topology levels for non-i386 arches, and add
> > helpers for topology enumeration and string conversion.
> >
> > Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
>
> [...]
>
> > diff --git a/qapi/machine.json b/qapi/machine.json
> > index bce6e1bbc412..7ac5a05bb9c9 100644
> > --- a/qapi/machine.json
> > +++ b/qapi/machine.json
> > @@ -1667,6 +1667,46 @@
> > '*reboot-timeout': 'int',
> > '*strict': 'bool' } }
> >
> > +##
> > +# @CPUTopoLevel:
>
> I understand you're moving existing enum CPUTopoLevel into the QAPI
> schema. I think the idiomatic QAPI name would be CpuTopologyLevel.
> Would you be willing to rename it, or would that be too much churn?

Sure, I'll rename it as you suggested.

> > +#
> > +# An enumeration of CPU topology levels.
> > +#
> > +# @invalid: Invalid topology level, used as a placeholder.
> > +#
> > +# @thread: thread level, which would also be called SMT level or logical
> > +# processor level. The @threads option in -smp is used to configure
> > +# the topology of this level.
> > +#
> > +# @core: core level. The @cores option in -smp is used to configure the
> > +# topology of this level.
> > +#
> > +# @module: module level. The @modules option in -smp is used to
> > +# configure the topology of this level.
> > +#
> > +# @cluster: cluster level. The @clusters option in -smp is used to
> > +# configure the topology of this level.
> > +#
> > +# @die: die level. The @dies option in -smp is used to configure the
> > +# topology of this level.
> > +#
> > +# @socket: socket level, which would also be called package level. The
> > +# @sockets option in -smp is used to configure the topology of this
> > +# level.
> > +#
> > +# @book: book level. The @books option in -smp is used to configure the
> > +# topology of this level.
> > +#
> > +# @drawer: drawer level. The @drawers option in -smp is used to
> > +# configure the topology of this level.
>
> docs/devel/qapi-code-gen.rst section Documentation markup:
>
> For legibility, wrap text paragraphs so every line is at most 70
> characters long.
>
> Separate sentences with two spaces.

Thank you for pointing this.

About separating sentences, is this what I should be doing?

# @drawer: drawer level. The @drawers option in -smp is used to
# configure the topology of this level.

Thanks,
Zhao