Dual SuperSparcs

Sun tests show that a second SuperSparc processor improves performance by 20 percent to 40 percent for most existing Solaris 2.3 applications. Once available, programs tuned for multiple processors will do even better. Sun points out that you don't have to see a performance doubling to justify a second processor: If the percentage performance increase for your applications is more than the percentage price increase for the additional CPUs, you come out ahead. If you order your system with two processors on one CPU board, the additional cost for the second CPU is around $1500, or 12 percent, over the base model list cost. However, if you add it later, you'll pay a steep $4500, or 37 percent, of the base price for a second processor board.

Near the end of my review of the SparcStations, I received and installed in the SparcStation 20M a second 50-MHz processor bo ard. Installation was simple because the system recognized and automatically worked with the new processor. Although I had no benchmarks ready to test multiprocessing, I did test around the edges of its potential using BYTE's Unix benchmarks. These tests are not multithreaded, nor are they designed to benefit from multiple processors, yet the second CPU provided an overall performance gain of around 12 percent. That fits with SPARC's higher estimates for more complex applications.

The best performance gain with multiple CPUs comes when you're running more than one application. With two tests running simultaneously (with a script), performance didn't differ markedly from when running one test with one CPU. As long as you run Solaris 2.x (which as yet has half the applications base of Solaris 1.x), a dual-processor system can run a fairly heavy-duty application in concert with other tasks with virtually no performance degradation.

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Illustration: Graph: BYTE Unix Benchmarks