May 14, 2012

Intel Rolls Out New Server CPUs

Michael Feldman

Intel Corp. has launched three new families of Xeon processors, joining the Xeon E5-2600 series the chipmaker introduced in March. These latest chips span the entire market for the Xeon line, from four- and two-socket servers, down to entry-level workstations and microservers. A number of HPC server makers, including SGI, Dell, and Appro announced updated hardware based on the new silicon.

The newest Xeon of greatest interest to high performance computing is the Sandy Bridge E5-4600 series, which is built for four-socket servers. At the CPU level, the E5-4600 is more or less identical to the E5-2600 for two-socket systems, both of which are available in 4-, 6-, and 8-core flavors, support 4 memory channels, include 40 lanes of integrated PCIe 3.0, and come with up to 20 MB of last level cache. The four-socket E5-4600 can support twice as much memory per system (up to 1.5 TB) as its two-socket counterpart, but that just serves to keep the per processor and per core memory ratio in line.

In normal times, the new four-socket Xeon would simply take the place of the older technology, in this case the Xeon E7 (“Westmere-EX”), but Intel has moved the new chip into a somewhat different role. According to Michele Fisher, a senior product marketing engineer at Intel, the E5-4600 is intended to complement the E7, rather than replace it. Specifically, the Sandy Bridge version is a “cost and density optimized” CPU for four-socket servers, which in this case is reflected in less cores (maxing out at 8 instead of 10 on the Westmere-EX), a lower memory capacity (1.5 TB instead of 2.0 TB), and less RAS support. It’s also less expensive. The price range on the new four-socket Xeons is $551 to $3,616; on the older Westmere E7 chips, it’s $774 to $4,616.

The idea, says Fisher, is to target the new four-socket CPUs for dense, scale-out systems in domains like HPC and telco, and to support growing geographies like China, which are especially cost-conscious. And because of their density and better energy efficiency, the new CPUs are especially suitable for four-socket blade servers. The older E7 chips will continue to be sold into more traditional enterprise systems, in particular, high-end transactional database machines, where the larger memory footprint and high reliability features are most appreciated.

Since the E5-4600 supports the Advanced Vector Extensions (AVX), courtesy of the Sandy Bridge microarchitecture, the new chip can do floating point operations at twice the clip of its pre-AVX predecessors. According to Intel, a four-socket server outfitted with E5-4650 CPUs can deliver 602 gigaflops on Linpack, which is nearly twice the flops that can be achieved with the top-of the-line E7 technology. That makes this chip a fairly obvious replacement for the E7 when the application domain is scientific computing.

Which explains why SGI is upgrading its Altix UV shared memory supercomputing platform from the E7 to the E5-4600. Also, since the UV has SGI’s custom NUMAlink interconnect and node controller, that system can scale well beyond the four sockets and 1.5 TB of cache coherent memory based on the native Intel chipset.

In fact, SGI’s new Sandy Bridge-based UV can scale up to 4,096 cores and 64 TB of memory in a single system. That’s twice the number of cores and four times the memory of the older Westmere-based UV. And because of the chip’s AVX support, peak flops per UV rack has doubled, from 5.4 to 11 teraflops.

SGI has already sold one of its new UVs to the COSMOS Consortium, a group that uses HPC to support origin-of-the-universe type research associated with Stephen Hawking’s cosmology work. Some of the simulations are designed to reveal the nature of the universe immediately after — as in one second after — the Big Bang. The computer will also support other cosmology research, including searching for planets outside our solar system.

Dell is also using the E5-4600, but in more conventional HPC gear. It’s putting the new Xeon into its four-socket PowerEdge M820 and R820, a blade and rackmount server, respectively. The M820 can house up to 10 full-height blades in 10U chassis, while the half-as-dense rackmount R820 puts a single four-socket server into a 2U box.

A couple steps down performance-wise from the E5-4600 is Intel’s new Sandy Bridge E5-2400, aimed at lower-end two socket servers. It’s designed to be a more energy-efficient alternative to the original two-socket E5-2600. It’s also considerably cheaper, with a price range of $188 to $1,440.

The E5-2400 series spans the same core counts as E5-2600, but gets by with one less memory channel (3), fewer PCIe lanes (24), and maxes out at half the memory (384 GB) of its older sibling. More importantly, they tend to be slower chips; the top-end E5-2440 is nearly full gigahertz slower (2.4 GHz) than the fastest E5-2600. But that translates into less power draw — from 60 watts on the low end part, up to 95 watts at the top end.

Their energy efficiency and cost make them suitable for scale-out clusters that don’t require a lot of single-threaded horsepower. Dell, for example, is using the E5-2400 processors in their new M420 blade, which is being positioned for some HPC-type workloads, especially animation and CGI rendering. The M420 is the first quarter-height dual-socket blade in the market; 32 of the mini-blades (1024 cores) can be squeezed into a 10U chassis. As with the four-socket gear, Dell is also offering a rackmount counterpart, the R420.

SGI is using the E5-2400 CPU as the base processor for its the Hadoop clusters, as well as in its Rackable server line for more general enterprise duty. For many Hadoop applications, which tend to be bound by data movement, rather than raw computational muscle, this chip could be a nice fit. And even though it’s slower than the mainline E5-2600 chips, SGI is still promising 22 percent better price-performance and 27 percent better performance/watt than the corresponding Westmere EP-based Hadoop gear.

The third new Xeon is the one-socket E3-1200 v2, a 22nm Ivy Bridge CPU for entry-level servers and workstations. Offered in dual-core and quad-core configurations, prices range from $189 to $884. The fastest part, at 3.7 GHz, offers quite respectable performance, but with only 8 MB of cache and a maximum memory capacity of 32 GB, the chip might be a bit of a stretch for HPC duty.

The family also includes two interesting new CPUs aimed at the microserver market, including Intel’s lowest powered Xeon, the E3-1220L v2. With a TDP of just 17 watts, that’s approaching ARM CPU territory. For example, Calexda makes a quad-core ARM chip for microservers that draws 5 watts, but that’s a 32-bit CPU, which limits its application in the server room rather substantially. The 64-bit E3 Xeon would have no such problem.

Intel is not positioning these new microserver Xeons for high performance computing; ostensibly they’re targeted for front-end web workloads, content delivery, and dedicated hosting. However, some creative server maker might be able to design a nifty little one-socket box with the E3-1220L v2 that could be used for some types of embarrassingly parallel codes. But since Intel would much rather sell its higher end E5 Xeons to its HPC customers, we’re not likely to see a Xeon-based microservers in supercomputers anytime soon.

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