Core Parking difference in Windows 7 and Windows 8
Tento článek bude výjimečně v angličtině. Rozhodli jsme se, že dáme zahraničnímu československy nemluvícímu čtenáři příležitost nahlédnout pod pokličku našeho stylu psaní a tvorby recenzí. Jedním z důvodů je někdejší nekorektní zjištění dobrého výkonu AMD Bulldozeru ve WinRARu oproti procesorům Core i7. Rádi bychom tímto i našim zahraničním čtenářům sdělili náš pohled na věc.
We decided to write an article in English (actually it's our first) to give a non-Czech/Slovak speaking reader the opportunity to look inside our writing style and review creation. One of the reasons for this is incorrectly measured exceptional performance of AMD Bulldozer over the Intel Core i7 processor. We would like to take the opportunity to show our point of view to our readers abroad.
Kapitoly článků
4. Core Parking difference in Windows 7 and Windows 8
5. Conclusion
There is another difference in Core Parking between Windows 7 and Windows 8. Look at default Core Parking for Core i7 (I'm sure you'll understand that "zaparkováno" in Czech means "parked" in English ;-).
Difference between Core Parking in idle: Windows 7 (left) and Windows 8 (right)
The difference is that Windows 7 parks all "hyper-threads" while Windows 8 parks all cores (including HT) excluding the first one. Windows 8 is also able to park AMD FX processor modules the same way:
Core Parking of AMD Bulldozer 8-core processor: Windows 7 (left, unable to park anything), Windows 8 (right)
Since the Core Parking feature is generally for energy saving and not for performance improvement, the AMD FX processor is normally favored in reviews by the Windows 7 operating system. In spite of that fact AMD Bulldozer failed to show some great performance, with the one exception, which is WinRAR.
We would like to show you what happens when you would like to change the affinity of cores to particular process in Windows 7 and 8 when Core Parking is enabled. As you will see, it makes an extraordinary mess in the performance and cores/threads utilizing. Not working really the way you would expect ;-). (The graph shows the encoding process, orange line represents 2nd pass while the beginning shows 1st pass of encoding).
Core Parking ON, affinity 11110000, Windows 7 (left), Windows 8 (right)
You would probably guess that Windows 8 works as expected in this situation while Windows 7 does something odd, namely park the threads that are assigned to the application. But look what happens in the 10101010 situation (ignore the spikes on the right picture, Windows 8 is far from final and far from perfect):
Core Parking ON, affinity 10101010, Windows 7 (left), Windows 8 (right)
Roles changed, Windows 7 works as expected while Windows 8 parks some threads that are set to work. Of course it has a big influence of the results:
Needless to say that very few people will probably set the affinity of process like that, we did it just for the demonstration purposes. And if someone would really want to do that, he will probably turn off the Core Parking at all.
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Kapitoly článků
4. Core Parking difference in Windows 7 and Windows 8
5. Conclusion
