CPU roadmap: server processors

In the world of processors, attention seems firmly focused on the fast-paced desktop and mobile markets. But that doesn't mean that there's nothing going on in server-land. Virtualisation extensions and multi-core support are now standard, with new architectures and fabrication technologies being implemented that will see the current generation of quad-core chips assigned to the history books in months rather than years.

As far as the players are concerned, the same companies that dominate the desktop market — Intel and AMD — also lead the server charge. Similarly, they've been playing the same game of leap-frog as new architectures and technologies have given first one and then the other a short-term advantage. Just a couple of years ago, for example, AMD appeared to take an unshakeable hold on the server market with its dual-core Opterons which were widely seen as technically superior to Intel's first attempts in this direction. However, that lead was soon lost as dual-core products based on Intel's quickly revamped Core micro-architecture started to ship. Since then, Intel has also beaten its rival to quad-core, leaving it with what looks like a winning hand at present.

That could change, with both chip-makers expected to introduce new processors this year. Also, each has published roadmaps showing further developments to 2010 and beyond. Increasing the number of processor cores is seen as the way ahead, together with architecture changes and other tweaks to allow this to happen.

It's important to note that, although Intel and AMD dominate the desktop processor market, they don't have it all their own way in the server space. Companies like IBM and Sun continue to chip away (sic) at that duopoly, with limited success.

So let's examine who's doing what, and what's coming up as the different vendors slug it out in the server processor ring.

In the Intel corner...
Keeping tabs on all the different Xeon and Itanium processors that Intel keeps pushing out to the server and HPC (High Performance Computing) markets is far from easy, but here goes.

At the time of writing (June 2008), Intel leads with its well-established family of Xeon server processors all now based on the Core micro-architecture, first introduced in 2006. Single-, dual- and quad-core products are readily available and can be broadly divided into three families: the Xeon Processor 3000 series for use in single-socket servers, the Xeon Processor 5000 series for 2-way systems and the Xeon Processor 7000 series for 4-way multi-processing and beyond.

All of the Xeons support Intel's virtualisation technology (Intel VT) and most of the current crop have been moved to Intel's 45-nanometre (nm) Hi-k metal gate silicon technology, which is the key component of the Penryn platform, enabling more cache to be put on each chip and other processing enhancements to be implemented. The latest to be ported is the Xeon 5400 series (launched in November 2007), comprising a family of quad-core processors for dual-processor (DP) systems available in both high and low energy (80W) implementations.

For high-end 4-way servers, Intel is currently shipping quad-core Xeon Processor 7300 series (Tigerton) chips based on the older 65nm technology. Tigerton is part of Intel's Caneland platform (launched September 2007) which includes a new chipset (Clarksboro) to enable it to support up to four quad-core processors — effectively giving up to 16-way SMP. It also incorporates a new point-to-point interface, giving each processor access to the full front-side bus bandwidth (1066MHz).

In the second half of 2008, Intel is expected to release a 45nm implementation of the Xeon 7000 Series processor, called Dunnington, which will simply plug into Caneland motherboards. This is now expected to be a 6-core rather than a quad-core chip, made up of 3 dual-core pairs on the same die with 3MB L2 and 16MB of L3 cache per pair. By upgrading to Dunnington, customers will effectively power up from 16- to 24-way SMP.

The forthcoming Dunnington CPU is designed for multi-processor Caneland servers: a four-way system with this 45nm processor will have 24 cores.

Further down the line (early 2009) Intel is set to introduce a totally new NUMA-based architecture that's designed to be a lot more scalable than Intel Core, enabling it to further increase the number of cores per chip (up to 16 or more) as well as help minimise power and cooling requirements. Known as Nehalem, the new architecture offers greater parallelism and enhanced multi-threading support. It will also incorporate a dedicated point-to-point interconnect (QuickPath) to link processors to each other and directly to memory — much like AMD's HyperTransport. An integrated DDR3 memory controller will also be included with three memory channels per processor.

By 2010 Nehalem processors are set to be shrunk even further onto 32nm dies (Westmere) after which, in accordance with the Intel's 'tick-tock' development cycle, the company is planning to introduce yet another architecture revamp (Sandy Bridge); among other enhancements, this will improve floating-point performance by incorporating Intel's 256-bit Advanced Vector Extension (AVX) technology.

Intel's 'Tick-Tock' development cycle in action: 45nm Nehalem architecture chips will shrink to 32nm ('tick') and then be superseded by the Sandy Bridge architecture ('tock').

Lastly, the ill-fated Itanium hasn't gone away. Officially now the Intel Itanium 9000 series, it too has been revamped with the latest Montvale implementation — a 90nm product available in both single- and dual-core formats. Montvale offers support for higher clock speeds than its predecessor (the Montecito) plus a faster frontside bus and low power requirements, and is designed for use on highly scalable SMP systems with up to 2,048 processors. A move to 65nm (Tukwila) is expected in 2009 with a 32nm implementation (Poulson) to follow.

In the AMD corner...
Like its Intel rival, AMD divides up its portfolio of 64-bit Opteron server processors according to the type of host system they're designed for. Broadly speaking, the Opteron 1000 Series is for single-socket servers and workstations, while the 2000 Series is for 2-way systems and the 8000 Series can be deployed in servers with up to eight sockets.

Support for AMD's virtualisation technology (AMD-V) is now standard on all Opterons but, as with Intel's Xeons, it's not always easy working out the current state of play. In general, however, second-generation dual-core Opterons have been available for some time in each series, as are third generation quad-cores (Barcelona) — although due to the late discovery of a major bug the quads only started to ship in March/April 2008. That was over six months later than planned and well behind rival Intel. AMD also lags behind Intel when it comes to low-energy implementations, only releasing the 55-Watt HE (High Efficiency) version of the new Opteron in May 2008.

The company has quietly dropped plans for an 8-core processor and no more new Opterons are expected until later in the year when the 65nm Barcelona product will be replaced by a slimmer 45nm implementation (Shanghai). Still a quad-core chip, Shanghai will also feature an update to AMDs inter-processor communication technology (coherent HyperTransport 3.0) and a tripling of the on-board L3 cache to 6MB.

Later this year, AMD's 45nm quad-core 'Shanghai' processor will replace the current generation of 65nm 'Barcelona' chips.

In a recent revamp of its roadmap, AMD also announced plans to ship a 6-core Opteron in the second half of 2009, possibly a year after the expected Dunnington ship date from Intel. Codenamed Istanbul, the 6-core AMD chip will be 45nm implementation that will be plug-compatible with existing Socket F quad-cores, making it easy for customers to upgrade.

Come 2010, however, AMD is planning to introduce a new socket platform (Socket G34, previously codenamed Maranello) with, among other enhancements, support for DDR3 memory and an additional (fourth) HyperTransport link. Two new processors are in development to fit this socket and both are 45nm designs, with estimated ship dates in the first half of 2010. One is slated to be a 6-core product (Sao Paulo), while the other (Magny-Cours) is set to have 12 cores to play with.

AMD's server/workstation roadmap has recently been revamped to include 6-core processors and a new Socket G34 (Maranello) platform, due in 2010.

In the other corners...
All of the leading server vendors (HP, Dell, IBM and Sun Microsystems) use Intel's Xeon and Itanium processors in their products. Moreover, in the last few years most of these vendors have also embraced AMD's chips, selling Opteron alongside Xeon products with a high degree of success — particularly to run Linux. However, IBM and Sun (together with partner Fujitsu) both continue to develop their own in-house processors, primarily for use in more specialised server, minicomputer and mainframe platforms.

IBM was arguably the first vendor to ship a multi-core chip, releasing the RISC based dual-core POWER4 back in 2000. Used in iSeries, pSeries and other proprietary IBM systems, development of the POWER (Performance Optimization With Enhanced RISC) platform has continued with the latest incarnation, the 65nm POWER6 — a dual-core chip released in May 2007 for use in up to 8-way systems.

IBM's POWER6 is a 64-bit dual-core processor with 790 million transistors running at up to 4.7GHz, with 8MB of on-chip Level 2 cache.

A POWER7 processor is also in development, as part of a 4-year US DARPA (Defence Advanced Research Projects Agency) contract awarded to IBM in 2006. Few details are available, but the new chip has been rumoured to be plug-compatible with the AMD Opteron (although this is not confirmed by IBM) and likely to appear around 2010.

As well as selling Intel/AMD powered x86 servers, Sun has also been experimenting with its own multi-core technology for a number of years. Its latest processors are the UltraSPARC T2 (originally codenamed Niagara 2) designed for use in single-socket rack and blade servers and the UltraSPARC T2 Plus (Victoria Falls) recently released (April 2008) for use in 2-way servers. Both are 65nm 8-core processors with a pair of on-board 10Gbps Ethernet ports and integrated cryptographic capabilities. A 16-core processor (Rock) is also in development for use in SMP servers with an expected 2009 ship date.

Sun's UltraSPARC T2 is an eight-core processor manufactured on a 65nm process.

Finally, it's worth noting that although systems powered by Sun UltraSPARC and IBM POWER processors have well-established niche markets, the chips themselves tend not to be adopted by other manufacturers. That honour goes to Intel and AMD who, between them, have the lion's share of the server and HPC processor markets. Moreover, that dominance continues to grow with increasing adoption of Opteron by the top vendors plus a recently announced joint Intel/Cray development initiative that will see even Cray supercomputers powered by industry-standard Xeon silicon in the future.