SCL Cluster Cookbook|
Motherboards and CPUS
|Intel Pentium II Processor|
Intel's inexpensive Celeron CPU with 128KB L2 cache may perform adequately, depending on the application. The Celeron's memory bus runs at 66MHz and its cache is one fourth the size of the Pentium II's. The Celeron's cache runs at the same speed as the processor, which helps overcome the penalty of the memory bus speed and small cache size. The stock Celeron may not be used in SMP systems, although with a hardware modification (which is reasonably easy to do using Socket 370 Celerons with "Socket 370 to Slot 1" converter boards such as the MSI MS-6905) it can be used in dual-CPU SMP systems.
Intel's Pentium II Xeon processors have a full speed cache of 512KB or 1024KB and a 100MHz memory bus. Xeons are expensive and require a different motherboard than the Pentium II or Celeron CPUs. Intel's 450NX chipset for the Xeon finally supports 64-bit PCI busses, which could improve communication performance on Gigabit-performance interconnects. The 450NX chipset also supports 4-way interleaving, which may help overall performance in an SMP system. Up to four Xeons can be used in an SMP system.
Intel-compatible CPUs are offered by vendors such as AMD and Cyrix, but they do not have comparable floating point performance.
Tom's CPU Guide provides a convenient comparison of Intel and compatible CPUs. Unfortunately, the CPU comparison doesn't appear to have been updated to include the newer Pentium II offerings.
The Compaq/Digital Alpha CPU is a strong competitor with the Intel CPUs. Our work with a cluster of 533MHz Alpha systems shows much higher floating point performance than can be obtained from Intel CPUs.
Pentium Pro Motherboard
The choice of CPUs seems to be the major issue, as it is one of the
most important components on the motherboard. The choice of L2 cache
(if any), chipset, and RAM may all depend on the CPU choice.
Some Digital Alpha systems offer a large third level (L3) of cache to help improve performance.
The choice of chipset may also decide whether non-parity, parity, or ECC memory can be used. In a large group of systems, we feel that it is important to use ECC memory because of the large number of individual components (memory chips) that could fail.
Beware of any chipset or processor limitations that cause the system to cache only a portion of the full amount of RAM on a system. Performance will be tremendously reduced when accessing regions of memory that are not cacheable. The older Pentium II's (233MHz-333MHz) integrated L2 cache will only cache up to 512MB of memory. The newer Pentium II (350MHz and up) and Pentium II Xeon CPUs are capable of caching 1GB to 8GB of RAM, depending on the Pentium II model and chipset used.
The processor and chipset define the memory speed and PCI bus speed. On Celeron and slower Pentium II's, the memory bus speed is 66MHz and the PCI bus speed is 33MHz. Newer Pentium II's and Xeons run the memory bus at 100MHz. A faster memory bus affects the RAM speed selection (and in turn, price) and improves memory bandwidth.
Tom's Chipset Guide gives a nice table describing each chipset's technical features.
The bottom half of Tom's Mainboard
Guide offers a set of motherboard performance comparisons and
There are many potential vendors; here's a quick, short list:
Appearance of any vendor in this list does not constitute endorsement of that vendor by Ames Laboratory.