A customizable simulator for workstation networks

We present a customizable simulator called netsim for high performance point to point workstation networks that is accurate enough to be used for application level performance analysis, yet is easy enough to customize for multiple architectures and software configurations. Customization is accomplished without using any proprietary information, using only publicly available hardware specifications and information that can be readily determined using a suite of test programs. We customized netsim for two platforms: a 16 node IBM SP-2 with a multistage network and a 10 node DEC Alpha Farm with an ATM switch. We show that netsim successfully models these two architectures with a 2-6% error on the SP-2 and less than 10% error on the Alpha Farm for most test cases. It achieves this accuracy at the cost of a 7-36 fold simulation slowdown with respect to the SP-2 and a 3-8 fold slowdown with respect to the Alpha Farm.