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Sun and IBM still Running with RISC

ibmAs the Hot Chips conference wraps up today, Internet News has a quick rundown of two engineering powerhouses and their insistence to continue producing RISC processors.  Sun and IBM have been long proponents of RISC architectures. IBM has garnered quite a bit of success with their latest Power series processors.  The current Top 500 list includes 55 systems or ~11%.  The latest Power 6 series has been pushed to 5Ghz, but only dual core at 65nm.  The latest in the Power series, the Power 7, will move to an eight core per socket model using a 45nm manufacturing technology.  They’ll package the Power 7 in up to 32 socket servers [256 cores].

The older chips used very large off-chip caches of up to 30MB, but pin constraints on the Power 7 made this impossible. The Power 7 will use on-die eDRAM that has a very low power draw but very high speeds. The chip will have up to 32MB of L3 cache with “private” memory stores accessible only to one core. These stores can be migrated to be physically closer to the core, giving the Power 7 up to five times less latency than a typical L3 cache.

sunConversely, Sun has had issues delivering their latest Sparc processors.  The latest to fall MIA was ‘Rock’, their eight core variant.  However, they’re trying to get back on track with ‘Rainbow Falls’.  The next generation in the Sparc series will come with up to 16 cores, each with independent L2 cache and four coherency units.

With 16 cores and an equal number of caches, the Rainbow Falls design looks something like a checkerboard and juggling all those caches is a huge challenge. To prevent L2 cache misses and optimize layout, Sun is adding a core to L2 Bank Crossbar (CCX), where two cores share a common port into a CCX, and the CCX connects all 16 L2 caches.

Sun’s hardware engineering fate is somewhat dependent upon what will happen with the eventual merger with Oracle.  For more info on the latest in RISC goodness, read the full article here.

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