Processors

Introduction
HPC Architecture
  1. Shared-memory SIMD machines
  2. Distributed-memory SIMD machines
  3. Shared-memory MIMD machines
  4. Distributed-memory MIMD machines
  5. ccNUMA machines
  6. Clusters
  7. Processors
    1. AMD Opteron
    2. IBM POWER5+
    3. IBM BlueGene processors
    4. Intel Itanium 2
    5. Intel Xeon
    6. The MIPS processor
    7. The SPARC processors
  8. Networks
    1. Infiniband
    2. InfiniPath
    3. Myrinet
    4. QsNet
    5. SCI
Available systems
  1. The Bull NovaScale
  2. The C-DAC PARAM Padma
  3. The Cray X1E
  4. The Cray XT3
  5. The Cray XT4
  6. The Cray XMT
  7. The Fujitsu/Siemens M9000
  8. The Fujitsu/Siemens PRIMEQUEST
  9. The Hitachi BladeSymphony
  10. The Hitachi SR11000
  11. The HP Integrity Superdome
  12. The IBM eServer p575
  13. The IBM BlueGene/L&P
  14. The Liquid Computing LiquidIQ
  15. The NEC Express5800/1000
  16. The NEC SX-8
  17. The SGI Altix 4000
  18. The SiCortex SC series
  19. The Sun M9000
Systems disappeared from the list
Systems under development
Glossary
Acknowledgments
References

In comparison to 10 years ago the processor scene has become drastically different. While in the period 1980--1990, the proprietary processors and in particular the vectorprocessors were the driving forces of the supercomputers of that period, today that role has been taken on by common off-the-shelf RISC processors and Intel x86 compatible processors. In fact there are only two companies left that produce vector systems while all other systems that are offered are based on RISC/EPIC CPUs or x86-like ones. Therefore it is useful to give a brief description of the main processors that populate the present supercomputers and look a little ahead to the processors that will follow in the coming year.

The RISC processor scene has shrunken significantly in the last few years. The Alpha and PA-RISC processors have disappeared in favour of the Itanium processor product line and, interestingly, the MIPS processor disappeared some years ago and now re-appears in the SiCortex systems (see the section on the SiCortex system). The disappearance of RISC processor families demonstrates a trend that is both worrying and interesting: worrying because the diversity in the processor field is decreasing severely and, with it, the choice for systems in this sector. On the other hand there is the trend to enhance systems having run-of-the-mill processors with special-purpose add-on processors in the form of FPGAs or other computational accelerators because their possibilities in performance, price level, and ease of use has improved to a degree that they offer attractive alternatives for certain application fields.

The notion of "RISC processor" has eroded somewhat in the sense that the processors that execute the Intel x86 (CISC) instruction set now have most of the characteristics of a RISC processor. Both the AMD and Intel x86 processors in fact decode the CISC instructions almost entirely into a set of RISC-like fixed-length instructions. Furthermore, both processor lines feature out-of-order execution, both are able to address and deliver results natively in 64-bit length, and the bandwidth from memory to the processor core(s) have become comparable to those of RISC/EPIC processors. A distinguishing factor is still the mostly much larger set of registers in the RISC processors.
Another notable development of the last few years are the placement of more than one processor core on a processor chip and the introduction of some form of multi-threading. We will discuss these developments for each of the processors separately.