Re: [PATCH v14 01/11] s390x/cpu topology: adding s390 specificities to CPU topology

[Pierre Morel <pmorel@linux.ibm.com>]

On 1/10/23 12:37, Thomas Huth wrote:
> On 05/01/2023 15.53, Pierre Morel wrote:
>> S390 adds two new SMP levels, drawers and books to the CPU
>> topology.
>> The S390 CPU have specific toplogy features like dedication
>> and polarity to give to the guest indications on the host
>> vCPUs scheduling and help the guest take the best decisions
>> on the scheduling of threads on the vCPUs.
>>
>> Let us provide the SMP properties with books and drawers levels
>> and S390 CPU with dedication and polarity,
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
> ...
>> diff --git a/qapi/machine.json b/qapi/machine.json
>> index b9228a5e46..ff8f2b0e84 100644
>> --- a/qapi/machine.json
>> +++ b/qapi/machine.json
>> @@ -900,13 +900,15 @@
>>   # a CPU is being hotplugged.
>>   #
>>   # @node-id: NUMA node ID the CPU belongs to
>> -# @socket-id: socket number within node/board the CPU belongs to
>> +# @drawer-id: drawer number within node/board the CPU belongs to
>> +# @book-id: book number within drawer/node/board the CPU belongs to
>> +# @socket-id: socket number within book/node/board the CPU belongs to
> 
> I think the new entries need a "(since 8.0)" comment (similar to die-id 
> and cluster-id below).

right

> 
> Other question: Do we have "node-id"s on s390x? If not, is that similar 
> to books or drawers, i.e. just another word? If so, we should maybe 
> rather re-use "nodes" instead of introducing a new name for the same thing?

We have theoretically nodes-id on s390x, it is the level 5 of the 
topology, above drawers.
Currently it is not used in s390x topology, the maximum level returned 
to a LPAR host is 4.
I suppose that it adds a possibility to link several s390x with a fast 
network.

> 
>>   # @die-id: die number within socket the CPU belongs to (since 4.1)
>>   # @cluster-id: cluster number within die the CPU belongs to (since 7.1)
>>   # @core-id: core number within cluster the CPU belongs to
>>   # @thread-id: thread number within core the CPU belongs to
>>   #
>> -# Note: currently there are 6 properties that could be present
>> +# Note: currently there are 8 properties that could be present
>>   #       but management should be prepared to pass through other
>>   #       properties with device_add command to allow for future
>>   #       interface extension. This also requires the filed names to 
>> be kept in
>> @@ -916,6 +918,8 @@
>>   ##
>>   { 'struct': 'CpuInstanceProperties',
>>     'data': { '*node-id': 'int',
>> +            '*drawer-id': 'int',
>> +            '*book-id': 'int',
>>               '*socket-id': 'int',
>>               '*die-id': 'int',
>>               '*cluster-id': 'int',
>> @@ -1465,6 +1469,10 @@
>>   #
>>   # @cpus: number of virtual CPUs in the virtual machine
>>   #
>> +# @drawers: number of drawers in the CPU topology
>> +#
>> +# @books: number of books in the CPU topology
>> +#
> 
> These also need a "(since 8.0)" comment at the end.

right again, I will add this.

> 
>>   # @sockets: number of sockets in the CPU topology
>>   #
>>   # @dies: number of dies per socket in the CPU topology
>> @@ -1481,6 +1489,8 @@
>>   ##
>>   { 'struct': 'SMPConfiguration', 'data': {
>>        '*cpus': 'int',
>> +     '*drawers': 'int',
>> +     '*books': 'int',
>>        '*sockets': 'int',
>>        '*dies': 'int',
>>        '*clusters': 'int',
> ...
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index 7f99d15b23..8dc9a4c052 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -250,11 +250,13 @@ SRST
>>   ERST
>>   DEF("smp", HAS_ARG, QEMU_OPTION_smp,
>> -    "-smp 
>> [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]\n"
>> +    "-smp 
>> [[cpus=]n][,maxcpus=maxcpus][,drawers=drawers][,books=books][,sockets=sockets][,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]\n"
> 
> This line now got too long. Please add a newline inbetween.

OK

Thanks.

Regards,
Pierre

-- 
Pierre Morel
IBM Lab Boeblingen