Benchmarking a Network of PCs Running Parallel Applications

We present a benchmarking study that compares the performance of a network of four PCs connected by 100 Mb/s Fast Ethernet running three different system software configurations: TCP/IP on Windows NT, TCP/IP on Linux and a light weight message passing protocol (U-Net Active messages) on Linux. For each configuration, we report results for communication micro-benchmarks and the NAS parallel benchmarks. For the NAS benchmarks, the overall running time using Linux TCP/IP was 12 to 500 percent less than the Windows NT TCP/IP configuration. We show that longer code paths and poor memory hierarchy utilization are responsible for this difference. Likewise, the Linux U-Net based message passing protocol outperformed the Linux TCP/IP version by 5 to almost 200 percent. We also show that using Linux U-Net we are able to achieve 125 micro-second latency between two processes using PVM. In addition, we show that poor memory system performance in the form of increased kernel and user mode cache misses contributes to NT’s poor performance on the NAS kernels. Finally, we report that the default math libraries supplied under NT (for both gcc and Visual C++) are substantially slower than the one supplied with Linux.