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The widening gap between central processing unit (CPU) speed and main memory speed has challenged high-performance computing for more than a quarter century. CPU designers have used more and more complex strategies to reduce the speed penalty of memory transactions, and they have employed more and more levels of larger and more sophisticated cache memories. Yet in all but the most “regular” computations, fast CPUs still seem to idle for too many cycles while they wait for memory to catch up.
In 2005, Sun Microsystems introduced the UltraSPARC® T1 (code-named “Niagara”) processor, which takes a completely different approach to dealing with memory latencies. Rather than trying to avoid memory stalls, a strategy that has not been wildly successful, the T1 accepts the fact that memory delays are inevitable and tries to improve throughput by doing useful work instead of simply waiting. The strategy has been a great success for applications such as IBM® Lotus® Domino®, which is both highly parallel and memory-intensive. Domino’s out-of-the-box performance is excellent, but there are still opportunities to tune both Domino (6.5 and up) and SunTM SolarisTM for even better throughput.
In this article, Eric Sosman, expert on Domino's performance on Solaris, frequent speaker, and published author, briefly describes the UltraSPARC T1 and its 2007 successor, the UltraSPARC T2, and offers some approaches for tuning Domino and Solaris to take advantage of the thread-rich environments that these processors provide.
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Eric Sosman
Staff Engineer
Sun Microsystems, Inc.
Eric Sosman has four decades of experience as a software engineer. For the last ten years, he has served as technical liaison between Sun and the Lotus engineering teams, and as Sun’s delegate to the NotesBench Consortium. His primary focus is Domino’s performance on Solaris. He was the very first to test Domino on the UltraSPARC T1 “Niagara” processor and he contributed snippets of code to Domino. Eric has spoken at various conferences, writes the annual “Domino on Solaris: Common Tuning Tips” guide, and is a member of the Computer Society of the IEEE. | |
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