Windows multi-threading performance issues on multi-core systems only

[Sergey Gromov]

dsimcha wrote:
> == Quote from Simen kjaeraas (simen.kjaras at gmail.com)'s article
>> dsimcha <dsimcha at yahoo.com> wrote:
>>> Timing with affinity for all 4 CPUs:  28390 milliseconds
>>>
>>> Timing with affinity for only 1 CPU:  533 milliseconds
>> Tested this on a Core 2 Duo, same options. OS is Windows 7, 64bit. It
>> scales roughly inverse linearly with number of threads:
>> 163ms for 1,
>> 364ms for 2,
>> 886ms for 4

Maybe you mean core 2 quad?

>> This is quite different from your numbers, though.
> 
> Yea, forgot to mention my numbers were on Win XP.  Maybe Windows 7 critical
> sections are better implemented or something.   Can a few other people with a
> variety of OS's run this benchmark and post their numbers?

Core 2 duo laptop, 1.8GHz, XP Pro:

860ms   1 core
11369ms 2 cores