Let us take a little break from the CES news with a load of bull — a download of Bulldozer. If you have an eerie sense of being in this situation before then you may in fact have a bad memory as it did in fact happen and it was only about a month ago. Microsoft released an update in mid-December to optimize their operating systems for AMD Bulldozer technology; that patch disappeared without any listed reason. As of today, we have access to both the patch as well as most of the reason for the delay in the first place.
You know: part of me wants to see a Bulldozer go 100MPH, and another part of me fears greatly.
The first order of business is to explain to those who have an AMD FX series, Opteron 4200 series, and/or an Opteron 6200 series processor how to increase their potential performance: KB 2646060 and KB 2645594 each contain a patch which will optimize Windows to the Bulldozer architecture for most users when both are applied.
It turns out that Microsoft pulled the Bulldozer update last month when discussions with AMD revealed that the patch would not provide the promised performance increases for most users. The problem specifically centers on the Core Parking feature within Windows 7 and Windows Server 2008 R2: after the hotfix in December was applied, Core Parking would still interfere with Bulldozer’s design by attempting to save power and sleep cores that were unused without understanding that Bulldozer cores are not typical cores. With Core Parking disabled for Bulldozer-based CPUs either through this hotfix or by changing your performance profiles to “High Performance” from the often default “Balanced” you would allow Bulldozer to run as it actually desires to run. According to how these bulletins are worded, should you have been on “High Performance” profile back in December before the hotfix was pulled you would have experienced what should only have been available starting today.
These performance increases are not for every application, however. AMD has stated that applications which are more sparsely multithreaded would benefit most from the update.
Workloads that are moderately threaded have the potential for uplift. This could include virtualization, database, or transactional environments that are “bursty” – a mixture of light and heavy transactions, or legacy applications that are by nature not very threaded. The more heavily threaded the application, the less the likely the uplift.
My intuition knowing this as well as the Core Parking issue is that once Windows finally wakes the Bulldozer core, your experience is maximal with the December patch; applications which only temporarily become multithreaded either do not wake the proper portions of the processor or wake the processor in time to be of maximum benefit.
It appears as if the removal of the hotfix last month was simply because AMD believed that while the patch was effective, it would not be correctly applied to the vast majority of customers without a second hotfix and thus give the appearance of little to no real benefits.