Intel charges premium for Xeon E7 scalability

Socket to me, Westmere

Go Westmere, young man

The Westmere cores on the Xeon E7 chips include some features not found in their Nehalem predecessors and that were originally shipped with the "Westmere-EP" Xeon 5600 processors for two-socket servers a year ago. These new features include on-chip electronics for running the Advanced Encryption Standard (AES) algorithm for encrypting and decrypting data and Trusted Execution Technology (TXT), just to name two.

The on-chip AES-NI encryption/decryption instructions radically improve the performance of the AES algorithm. Software giant Oracle says it is seeing an order of magnitude performance increase on encryption within its 11g R2 database using this feature. The TXT feature is borrowed from Intel's vPro-capable business-class PCs and is being added to Intel's server processors to harden server virtualization hypervisors against malicious software insertions prior to the hypervisor booting up.

On a conference call announcing the processors, Kirk Skaugen, general manager of Intel's Data Center Group, said that some more machine check architecture (MCA) functions were being added to the Xeon E7s to make them suitable for mission critical workloads. Skaugen called out double device data collection as one such new RAS feature. This DDDC feature, which allows a system to correct from two memory errors without crashing, was slated for the original "Tukwila" Itaniums back in 2008. Tukwila, now called the Itanium 9300, was launched in February 2010.

All of the Xeon E7 processors support Intel's HyperThreading, which presents two execution threads to software for each physical core in the processor. In some cases, HyperThreading can improve the performance of workloads, and in other cases it actually hinders performance. But in the x64 core wars, Intel is committed to using a mix of ever-increasing core counts with HyperThreading, rather than just naked cores. Advanced Micro Devices has been allergic to any kind of simultaneous multithreading to its Opteron server chips, and it seems less inclined than ever with its future "Bulldozer" Opterons, due to start shipping for revenue in the second quarter. All of the Xeon E7s except the E7-8837, the smallest of the eight-socket capable processors, have HyperThreading.

All but two of the Xeon E7 chips support Intel's Turbo Boost 2.0 technology, which allows for the clock speed of a core to be goosed if the other cores in the chip are not working hard. The exact Turbo Boost bump was not available at press time, but we will track this data down.

Another important feature of the Xeon E7s is not on the chip, but next to it. There are two new "Millbrook" memory buffer chips that are used in conjunction with the Xeon E7 processors. The new 7510 and 7512 buffer chips allow for a four-socket machine to scale up to 2TB of main memory using 32GB DIMMs, and the 7512 chip supports 1.35 volt memory. With a four-socket machine sporting 64 memory slots, and the low-voltage memory consuming about 1 watt less per stick compared to 1.5 volt memory, it can really start adding up. The "Boxboro" 7500 chipset, which is shared between the Xeon 7500, Xeon E7, and Itanium 9300 processors, can scale gluelessly (meaning without having to slap on an additional supercontroller chip) to eight sockets, 128 memory slots, and 4TB of main memory. The new Millbrook controllers also allow a two-socket E7-2800 machine to have 32 memory slots and support up to 1TB of main memory without resorting to memory extension ASICs like those developed by IBM, Cisco Systems, and Dell for last year's Xeon 7500-based servers.

Generally speaking, the Xeon E7s offer roughly 40 per cent more performance than their Xeon 7500 predecessors. The shrink to 32 nanometers has allowed Intel to add two more cores, crank the clock speeds by a bit, and also boost the L3 cache on chip from 24MB to 30MB. All of these factors contribute to the performance increase. Obviously, mileage will vary by workload.

Skaugen says that the Xeon E7 chips have been shipping for around 100 days and that 19 vendors will have 35 systems out the door within the next 30 to 45 days. We'll be looking at as many of these as we can to tell you all about them. ®

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