Re: [PATCH v22 13/20] docs/s390x/cpu topology: document s390x cpu topology

[Thomas Huth]

On 01/09/2023 17.58, Nina Schoetterl-Glausch wrote:
> From: Pierre Morel <pmorel@linux.ibm.com>
>
> Add some basic examples for the definition of cpu topology
> in s390x.
>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
> Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
> ---
...
> diff --git a/docs/devel/s390-cpu-topology.rst b/docs/devel/s390-cpu-topology.rst
> new file mode 100644
> index 0000000000..70633f30cb
> --- /dev/null
> +++ b/docs/devel/s390-cpu-topology.rst
> @@ -0,0 +1,171 @@
> +QAPI interface for S390 CPU topology
> +====================================
> +
> +The following sections will explain the QAPI interface for S390 CPU topology
> +with the help of exemplary output.
> +For this, let's assume that QEMU has been started with the following
> +command, defining 4 CPUs, where CPU[0] is defined by the -smp argument and will
> +have default values:
> +
> +.. code-block:: bash
> +
> + qemu-system-s390x \
> +    -enable-kvm \
> +    -cpu z14,ctop=on \
> +    -smp 1,drawers=3,books=3,sockets=2,cores=2,maxcpus=36 \
> +    \

This empty line first confused me, but after reading the other examples 
later, I now think it is done on purpose, right? I'd maybe rather remove it 
in this example here anyway, it's not that big that you need a visual 
separation here.

> +    -device z14-s390x-cpu,core-id=19,entitlement=high \
> +    -device z14-s390x-cpu,core-id=11,entitlement=low \
> +    -device z14-s390x-cpu,core-id=112,entitlement=high \
> +   ...
...
> diff --git a/docs/system/s390x/cpu-topology.rst 
> b/docs/system/s390x/cpu-topology.rst
> new file mode 100644
> index 0000000000..78b98f978a
> --- /dev/null
> +++ b/docs/system/s390x/cpu-topology.rst
...
> +Examples
> +++++++++
> +
> +In the following machine we define 8 sockets with 4 cores each.
> +
> +.. code-block:: bash
> +
> +  $ qemu-system-s390x -m 2G \
> +    -cpu gen16b,ctop=on \
> +    -smp cpus=5,sockets=8,cores=4,maxcpus=32 \
> +    -device host-s390x-cpu,core-id=14 \
> +
> +A new CPUs can be plugged using the device_add hmp command as before:
> +
> +.. code-block:: bash
> +
> +  (qemu) device_add gen16b-s390x-cpu,core-id=9
> +
> +The core-id defines the placement of the core in the topology by
> +starting with core 0 in socket 0 up to maxcpus.
> +
> +In the example above:
> +
> +* There are 5 CPUs provided to the guest with the ``-smp`` command line
> +  They will take the core-ids 0,1,2,3,4
> +  As we have 4 cores in a socket, we have 4 CPUs provided
> +  to the guest in socket 0, with core-ids 0,1,2,3.
> +  The last cpu, with core-id 4, will be on socket 1.

I'd suggest to write "cpu" with capital letters for consistency.

Anyway:
Reviewed-by: Thomas Huth <thuth@redhat.com>