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The basic building block of Bulldozer is the dual-core module, pictured below. AMD wanted better performance than simple SMT (ala Hyper Threading) would allow but without resorting to full duplication of resources we get in a traditional dual core CPU. The result is a duplication of integer execution resources and L1 caches, but a sharing of the front end and FPU. AMD still refers to this module as being dual-core, although it's a departure from the more traditional definition of the word. In the early days of multi-core x86 processors, dual-core designs were simply two single core processors stuck on the same package. Today we still see simple duplication of identical cores in a single processor, but moving forward it's likely that we'll see more heterogenous multi-core systems. AMD's Bulldozer architecture may be unusual, but it challenges the conventional definition of a core in a way that we're probably going to face one way or another in the not too distant future.

A four-module, eight-core Bulldozer

The bigger issue with Bulldozer isn't one of core semantics, but rather how threads get scheduled on those cores. Ideally, threads with shared data sets would get scheduled on the same module, while threads that share no data would be scheduled on separate modules. The former allows more efficient use of a module's L2 cache, while the latter guarantees each thread has access to all of a module's resources when there's no tangible benefit to sharing.

This ideal scenario isn't how threads are scheduled on Bulldozer today. Instead of intelligent core/module scheduling based on the memory addresses touched by a thread, Windows 7 currently just schedules threads on Bulldozer in order. Starting from core 0 and going up to core 7 in an eight-core FX-8150, Windows 7 will schedule two threads on the first module, then move to the next module, etc… If the threads happen to be working on the same data, then Windows 7's scheduling approach makes sense. If the threads scheduled are working on different data sets however, Windows 7's current treatment of Bulldozer is suboptimal.

AMD and Microsoft have been working on a patch to Windows 7 that improves scheduling behavior on Bulldozer. The result are two hotfixes that should both be installed on Bulldozer systems. Read on for our take on what these hotfixes do to Bulldozer's Windows 7 performance.

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With the release of AMD’s Radeon HD 7970 it’s clear that AMD has once again regained the single-GPU performance crown. But while the 7970’s place in the current GPU hierarchy is well established, we’re still trying to better understand the ins and outs of AMD’s new Graphics Core Next Architecture. What does it perform well at and what is it weak at? How might GCN scale with future GPUs? Etc.

Next week we’ll be taking a look at CrossFire performance and the performance of AMD’s first driver update. But in the meantime we wanted to examine a few other facets of the 7970: the impact of PCIe bandwidth on performance, overclocking our reference 7970 (and the performance impact thereof), and what AMD is doing for anti-aliasing with the surprise addition of SSAA for DX10+ along with an interesting technical demo implementing MSAA and complex lighting side-by-side. So let’s get started.

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AP – Bloggers and activists from China, the Middle East and Latin America said Friday they were afraid that new Twitter policies could allow governments to censor messages, stifling free expression.

,Activists and bloggers fear Twitter censorship
(AP)
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Back in November, Samsung announced its next generation Exynos 5250 SoC based on ARM’s Cortex-A15 architecture. Samsung dropped the ball today during its earnings call that the Exynos 5250 has begun sampling and should hit mass production in Q2 2012

Just to recap, the Exynos 5250 is a 32nm dual-core Cortex-A15 SoC running at 2.0 Ghz. Memory bandwidth is a staggering 12.8 GB/s and allows it to drive up to WQXGA (2560×1600) resolution displays. As we reported back in November, compute performance should easily be twice that of the 1.5Ghz dual-core Cortex-A9-based Exynos 4210 and graphics performance is expected to be a four-fold improvement. 

However, not much is known about the GPU at this moment; but if the Exynos 4210 was anything to go by, we could see ARM's Mali T-604 based on their new Midgard architecture handling the pixel pushing duties. The Exynos 4210 packed a Mali-400 MP4 GPU, while its predescessor, Hummingbird, used a PowerVR SGX540 GPU. Samsung does have licenses to other GPU designs from ARM and Imagination Technologies, so at this point, the GPU in the Exynos 5250 could be anybody's guess.

The next generation SoC race is definitely heating up with silicon from major players such as Qualcomm (Snapdragon S4 "Krait") and Texas Instruments (OMAP 5) all expected to ramp up production soon, with devices expected in Q3/Q4 2012. Of course, what Apple could be doing with its A6 chip is entirely another story.

Source: GSMArena

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