> Other way around. Modern processors are in instructions per clock. On > raw CPU power it doesn't just beat the mainframe - it steamrollers them. > Your I/O bus is typically PCI however so you are limited to about > 100Mbytes/second I/O throughput in the real world.
I would regard 100Mb/sec as a peak (instantaneous) transfer rate. Throughput will be only a fraction of that. On some tests only a small fraction. I looked at PC benchmarking quite seriously a few years back. It's very difficult because the design assumptions for a single-user system are so very different from those for a multi-user system. One case in point was OS2, which makes heavy use of background threads for housekeeping purposes. Windows 95 does something similar for cache management. Drive either with a synthetic workload and they're taken out of their design envelopes - both will run into critical resource shortages even in well-configured systems and show 'knee of the curve' phenomena. At one point Ziff Davis was actually running word processing 'benchmarks' using driving systems to simulate 40,000 keystrokes a minute - obviously a real world test. The issue is partly that the Intel processor is overpowered for the majority of purposes. Remember the 386/387 combination? From a logical point of view it made sense - only those who needed serious number-crunching power would buy the 80387 Co-processor. But it's actually cheaper to integrate the function on a standard chip - Intel saves dieing for a second chip, the motherboard manufacturers save the cost of an extra socket, and the users save having to find, purchaes and install a high-value static senstive component. The functionality and the performance are indeed there, but they are of no benefit to 99.999% of the chip's purchasers. Making an issue out of it as a 'superiority' of that platform distracts purchasers from price/benefit issues that are much more relveant to their environments, and does the industry as a whole a disservice. Performance measurement should be left to those who know what they're doing. The first step is to define terms of measurement, and these must be related to real world and real user issues, so that the results are relevant to their audience. -- Phil Payne http://www.isham-research.com +44 7785 302 803 +49 173 6242039
