Abstract

3Com Corporation commissioned The Tolly Group to evaluate the effect various Token Ring adapters have on application throughput in an NT 4.0 environment. The Tolly Group benchmarked the performance of Token Ring PCI adapter pairs from 3Com, IBM Corp., Madge Networks and Olicom, Inc. 

With advances in silicon integration, it is not uncommon to see Token Ring adapters running at or near wire speed, even at smaller frame sizes. As wire-speed through- put becomes standard fare on adapters and multitasking environments become more prevalent, the impact that throughput has on local application performance rises in importance. 

In 32-bit OS environments like NT, adapter cards that consume excessive CPU cycles deny that resource to local applications. For example, a LAN adapter consuming 90% of a PC’s CPU during a file transfer forces the CPU to neglect other tasks. The performance of CPU-intensive applications running in the foreground will suffer until the file transfer completes. On the other hand, an adapter that delivers slightly lower throughput but consumes only 50% of the CPU’s performance to accomplish that same file transfer, will allow the user to run an application concurrently. Quantifying CPU consumption provides network managers with valuable information. 

The Tolly Group devised a test suite that measures the performance of a foreground application while the LAN adapter performs a series of file transfers. To determine application performance, The Tolly Group recorded the average run-time required to complete an automated test script. This script was devised so that a series of search and replace edits were made to an MS Word 97 document. These CPU-intensive (MS Word 97) functions were deliberately used to determine how the foreground (MS Word 97 document. These CPU-intensive (MS Word 97) functions were deliberately used to determine how the foreground (MS  Word 97) and background (file transfer) applications vie for CPU resources. 

Each workstation/server session communicated using TCP/IP via a single 16 Mbit/s Token Ring LAN. All throughput tests were conducted using matching pairs of adapters in the workstation and in the server. Testing was performed in February and March 1998.