Re: [Xen-devel] [PATCH v2 2/2] xen: fill topology info for all present cpus

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.09.18 at 09:38, <jgross@xxxxxxxx> wrote:
> On 03/09/18 15:41, Jan Beulich wrote:
>>>>> On 31.08.18 at 17:22, <jgross@xxxxxxxx> wrote:
>>> The topology information obtainable via XEN_SYSCTL_cputopoinfo is
>>> filled rather weird: the size of the array is derived from the highest
>>> online cpu number, so in case there are trailing offline cpus they
>>> will not be included.
>>>
>>> On a dual core system with 4 threads booted with smt=0 without this
>>> patch xl info -n will print:
>>>
>>> cpu_topology           :
>>> cpu:    core    socket     node
>>>   0:       0        0        0
>>>   1:       0        0        0
>>>   2:       1        0        0
>>>
>>> while with this patch the output is:
>>>
>>> cpu_topology           :
>>> cpu:    core    socket     node
>>>   0:       0        0        0
>>>   1:       0        0        0
>>>   2:       1        0        0
>>>   3:       1        0        0
>>>
>>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
>> 
>> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
>> for x86. I'd like this to have an ARM ack as well, though, for
>> there possibly being differences in how cpu_present_map is
>> handled in their case. In particular I notice that the only access
>> to the variable is in smp_prepare_cpus().
> 
> How relevant is that information for arm at all?
> 
> cpu_to_core(i) et al always return 0. So topology information is not
> really helpful.

Stefano, Julien?

Jan



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