[fpc-devel] AMD & Intel CPUCount

[Mark Morgan Lloyd]

Mark Morgan Lloyd wrote:
> Ludo Brands wrote:
>> On 27/12/2012 23:06, Ewald wrote:
>>> Oh, and the important part: The function has been tested on a Core 2 Duo
>>> and an Intel i7, and works correctly. If someone would be so kind to
>>> test it on some other CPU's that would be great! [I'm not 100% of the
>>> hexadecimal of `AuthenticAMD` you see]
>>>
>> Inconsistent results here with hyperthreading:
>> Xeon W3530 (4 cores hyperthreading) reports #CPU cores: 8. 
>> /proc/cpuinfo lists 8 processors and 4 cpu cores
>> Intel Atom 230 (1 core hyperthreading) reports #CPU cores: 1 while 
>> /proc/cpuinfo reports 2 processors and 1 cpu core.
> 
>> AMD Athlon X2 5600+ reports #CPU cores: 2. /proc/cpuinfo reports 2 
>> processors and 2 cores.
> 
> Also be careful of the situation where an OS supports hot-pluggable CPU 
> cards and has been told to shut one down for maintenance. Solaris 
> definitely does this on SPARC, I don't know about its position on x86, 
> and I don't know about Linux's general position.

Also somebody needs to check the situation with VMWare, Qemu etc., since 
they might be uncomfortable virtualising CPUID.

I've just checked and taskset is supported on zLinux, so I'm fairly 
confident that the API that underlies it is universal on Linux 2.6+: I 
really do think that that's what should be used for this job.

-- 
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]