Re: [Qemu-devel] [RFC PATCH v2] PPC: smp: autodetect numbers of threads per core

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 01/11/2014 01:25 AM, Alexander Graf wrote:
> 
> On 10.01.2014, at 15:21, Mike Day <ncmike@ncultra.org> wrote:
> 
>> On Fri, Jan 10, 2014 at 9:13 AM, Alexey Kardashevskiy <aik@ozlabs.ru>
>> wrote:
>>> On 01/11/2014 01:00 AM, Alexander Graf wrote:
>> 
>>>> Can't we determine the number of "default threads" at a common
>>>> place, preferably derived from cpu type?
>>> 
>>> We can do anything. I asked how exactly as I really (really) do not 
>>> understand the details.
>>> 
>> 
>> Are you suggesting we create a dictionary with all the cpu type 
>> information stored in it (stepping, cores, threads, memory channels,
>> caches) that we need to keep updated?
> 
> We can always talk in extremes :). Today we have a dictionary of core
> types in QEMU. If a certain core type comes with a specific number of
> threads, that's a property of the core, no?


No, the max smt number comes from cap_ppc_smt, not from CPU type. PR KVM
may return something different (what does it return?) and TCG definitely
will not allow anything but 1. Up to the accelerator, not a CPU class.


-- 
Alexey