Microsoft Posts Correct Hotfix For AMD Bulldozer Processors

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Microsoft Posts Correct Hotfix For AMD Bulldozer Processors

Post by Apoptosis » Wed Jan 11, 2012 3:29 pm

Microsoft has posted a hotfix for the core scheduler for AMD “Bulldozer” based processors, including AMD FX series desktop processors. AMD has posted a blog on to provide guidance on performance expectations and installation instructions (the blog is also attached for your convenience).

How to install:
Early Results Achieved with AMD FX Processor Using Windows® 7 Scheduler Update
Some of you may remember that AMD FX processors use a unique dual-core module
architecture codenamed “Bulldozer”, which current versions of Windows® 7 were not
specifically architected to utilize. In essence, for those with an AMD FX-8150 Processor, for
example, Windows 7 sees the eight available cores and randomly assigns threads to them.

In initial testing of the upcoming Windows 8 operating system, we’ve seen performance
improvements of up to 10% in some applications, when compared to Windows 7. This is
because the system correctly recognizes the AMD FX processor architecture and cores. Thanks
to close collaboration between Microsoft and AMD, Microsoft recently completed back-porting
some of the Windows 8 scheduler code for AMD FX processors into a hotfix for Windows 7.
So if you have an AMD FX processor, here’s what you can do to update your version of
Windows 7:

1) Download the scheduler update (KB2645594) and install. This will tell the scheduler
that your AMD FX processor contains dual-core modules (in fact this is similar to the
SMT path that the other guys use). In essence, threads 1-4 now get assigned to their
own module first.

2) Download the core parking scheduler update (KB2646060) and install. This will prevent
Windows 7 shutting down unused cores prematurely when there are threads to be
assigned (there’s a performance penalty parking and then un-parking a core).
The best possible cases for improvement are applications that use ½ cores in your AMD FX
processor. In our testing using the AMD FX-8150 processor, we found the best improvement in
wPrime, Left 4 Dead 2, and Lost Planet.

Our testing shows that not every application realizes a performance boost. In fact, heavily
threaded apps (those designed to use all 8 cores), get little or no uplift from this hotfix – they are
already maxing out the processor. In other cases, the uplift averages out to a 1-2 percent uplift.
But heck, it is free performance, and this is the scheduler model that will be used in Windows 8
(along with some further enhancements), so why not add it to your list of downloads?

If you have an AMD FX processor, head over to Microsoft and grab the free updates.
An Update for your 2012 Schedule(r)

January 11, 2012

Tis the season of resolutions! And a top resolution for 2012 is to get organized. For people, a central part of getting organized is learning how to improve scheduling your time to fit all the tasks at hand. Improving scheduling is not just a human thing – from an operating system (OS) viewpoint, better scheduling means that threads, processes or data flows are given more efficient access to system-level resources.

Our new AMD Opteron 6200 and 4200 Series processors are on the road to achieving optimal efficiency in 2012 with the recent release by our OS partners of improved scheduling techniques for their popular operating systems.

Let’s take a first look at Windows. Currently, the CPU scheduling techniques used by Windows Server 2008 R2 SP1 are not optimized for the module architecture of the AMD Opteron 6200 and 4200 Series processors. This means that certain multi-threaded workloads will not be optimally distributed between cores, which can result in decreased system performance.

Microsoft has just posted a hotfix for Windows Server 2008 R2 SP1 documented in KB2645595 that enlightens the OS kernel to the AMD Opteron 6200 and 4200 Series topology so that the kernel can do a better job of scheduling threads to the processor cores. This patch leverages work that AMD and Microsoft have done cooperatively for future versions of the Windows kernel, and can be applied as desired by users running Windows Server 2008 R2 SP1. Below you’ll find links to the patches:

What are the performance gains that can be expected from this patch? It depends. 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. We recommend that interested users apply the patch to a test system and see how their workload responds.

If we switch over to the Linux world, Red Hat Enterprise Linux (RHEL) 6.2 was released on Dec 6, 2011. RHEL 6.2 is another OS that is “enlightened” for the AMD Opteron 6200 and 4200 Series processors. It delivers higher levels of efficiency realized through resource management and performance optimization and enables enhanced business agility through more flexibility for virtualized and clustered environments.

AMD works closely with Microsoft, Red Hat and the Linux Open Source Community to drive enhancements for our processors at the operating system level. Our resolution is to get users to evaluate our AMD Opteron 6200 and 4200 Series processors with these new “enlightened” OSs.
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Re: Microsoft Posts Correct Hotfix For AMD Bulldozer Process

Post by CoachAub » Thu Jan 12, 2012 6:27 pm

I'm curious to see the benchmarks post-hotfix. I've felt that the chip was a little ahead of the OS and other software (benchmarking), design-wise from all I've read. That doesn't change the fact that it was majorly disappointing and even with the mentioned percentage of improvements from the hotfix, it still remains so. The point I'm making is that we are on the road to a better product. When you hear 8 cores--you think wow---nearly double the capability of a quad-core!!! At least you hope so. To have older model quad-cores compete with it, is just plain bad. My Phenom 2 970 overclocked to 4ghz on air can run stable and would give the 8120 a run for its money for sure. I'm hoping that the hotfix separates the old from the new more than anything, regardless of where they match-up with Intel's chips.
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