This article was published in the January 2015 issue of Maximum PC. For more trusted reviews and feature stories, subscribe here.
Frequently, the out-of-reach tech of today becomes mainstream a short way down the road
Although few Maximum PC readers actually build our annual Dream Machine, it’s still fun to see what a no-compromise machine looks like. Sooner than you think, equally powerful PCs will be on sale at Best Buy for a few hundred bucks.
For the same reasons, high-end microprocessors are a fascinating study. Designed for modern mainframes (“enterprise servers”) and gym-sized supercomputers, these specialized chips stop at nothing to deliver kickass performance. Their innovations often trickle down into mass-market processors several years later.
Two new big-iron processors are Fujitsu’s SPARC64 XIfx and Oracle’s SPARC M7. Both are compatible with the SPARC architecture pioneered by Sun Microsystems in the ‘80s. They’re relics from a bygone age when Intel’s x86 architecture and Microsoft Windows didn’t rule the world, but they still survive, and they’re still innovating. Fujitsu designs its own SPARC-compatible chips, and Oracle took over SPARC development after buying Sun in 2010.
Common folk can’t buy these things. Fujitsu designed its 34-core SPARC64 XIfx for its own supercomputers, which are sold only to governments and perhaps a few rich corporations. Oracle’s 32-core SPARC M7 will be more widely available in business servers, but is optimized to run Oracle’s enterprise database software. Nevertheless, both chips have features that breed envy.
Maximum PC’s Dream Machine can’t compete with Oracle’s 32 cores.
Fujitsu’s SPARC64 XIfx is the first processor to use Micron’s Hybrid Memory Cubes. Each cube is a stack of DRAMs with a proprietary interface. The SPARC64 XIfx can link to eight of these cubes to provide up to 240GB/s of peak DRAM bandwidth. By contrast, Intel’s Core i7-4960X Extreme Edition in the 2014 Dream Machine provides only 59.7GB/s, and the Dream Machine’s Core i7-4790K has only 25.6GB/s. (Feeling constipated?)
Another unusual SPARC64 XIfx feature is its layout. Its 34 cores occupy two 17-core clusters, each with 16 primary cores, one “assistant core,” 12MB of L2 cache, and private interfaces to four memory cubes. The assistant runs the control software, freeing the primary cores for computations. Physically, the XIfx isn’t a heterogeneous processor—all 34 cores are the same—but they shoulder different duties. This goes beyond the “affinity” concept in which a program prefers to run on a particular core.
Meanwhile, Oracle’s SPARC M7 sets a record by integrating more than 10 billion transistors. By comparison, the Core i7-4960X looks dwarfish with only 1.86 billion. Even when fabricated in advanced 20nm process technology, the M7 will have a huge die (700mm2, by my estimate). But it’s got more than 70MB of cache and 32 cores, and each core runs eight threads. Each chip has 341GB/s of memory bandwidth using 16 channels of DDR-2667 DRAM. Not enough? M7 supports systems with up to 64 sockets—up to 2,048 cores, 4.4GB of cache, 16,384 threads, and 128TB of DRAM. Now that’s a Dream Machine!
For me, the most fascinating M7 feature is real-time data integrity checking. It can supplement every 64-byte block of data with metadata that includes a version identifier. This follows the code from main memory to the caches and through the on-chip multicore network. The M7 compares each identifier with a valid reference and triggers an exception on any mismatch, helping to keep out buggy or malicious code.
High performance is expected from big iron, but security at every level is becoming equally important. And that’s what I’d like to see trickle into my little iron.
Tom Halfhill was formerly a senior editor for Byte magazine and is now an analyst for Microprocessor Report.
From maximumpc
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