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Last month, AMD launched their Bulldozer architecture on desktops, and the result was rather underwhelming; however, there are plenty of indications that Bulldozer simply wasn't architected to excel at desktop use models. AMD's "Interlagos" Opteron is now available, doubling the core count of the desktop part and placing its sights firmly on the enterprise server market.</p>
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The massive Multi Chip Module (MCM) contains eight processor cores (&ldquo;modules&rdquo; as AMD likes to call them) and can process 16 integer and 16 floating point threads per cycle. Each of the 16 integer threads gets their own integer cluster, complete with integer executions units, a load/store unit, and an L1-data cache. The Cluster Multi-Threading (CMT) architecture of Bulldozer should be perfectly suited for server applications that are mostly limited by memory accesses and integer processing. The 16 floating point threads have to share eight clusters of two 128-bit FP units, but those units can process FMAC and AVX instructions; recompile your HPC application with an FMAC and/or AVX capable compiler and the chip could become an HPC monster as well.</p>
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Server applications also like large caches, and Interlagos has plenty of SRAM cells. The Interlagos package has 32MB cache onboard (L2 and exclusive L3 combined). If all caching fails, it can access four memory channels of DDR3-1600, good for 51.2GB/s of theoretical bandwidth per chip. AMD also added power gating to the cores, so inactive cores can enter a very deep (C6) sleep state and save quite a bit power. This should significantly reduce power in idle and light loads.</p>
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With all of that potential, the initial clock speeds that AMD could be fit inside a 115W TDP envelope are a bit underwhelming. The fastest 115W Interlagos part right now, the Opteron 6276, has a 2.3GHz base clock. The current Opteron 6276 reaches the same clock speed at the same TDP using a less advanced 45nm SOI process. However, the longer pipeline of the new Bulldozer architecture allows the chip to use Turbo Core to boost to 2.6GHz when running most server workloads, and if only half of the cores are active, the chip is capable of 3.2GHz.</p>
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The initial desktop launch of Zembezi may have left us wanting more, and Interlagos might offer that. For server workloads at least, this all looks very promising. Let's see what the first "Bulldozer" based Opterons can do.</p>

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Source: AnandTech
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