The perpetual motion of parallel performance
How can the expected interactions between caller and implementation be guaranteed?
Web site performance data has never been more readily available.
The USE method addresses shortcomings in other commonly used methodologies.
Increasing parallelism demands new paradigms.
Improving the performance of complex software is difficult, but understanding some fundamental principles can make it easier.
Think you've mastered the art of server performance? Think again.
The modern Unix server floor can be a diverse universe of hardware from several vendors and software from several sources. Often, the personnel needed to resolve server floor performance issues are not available or, for security reasons, not allowed to be present at the very moment of occurrence. Even when, as luck might have it, the right personnel are actually present to witness a performance “event,” the tools to measure and analyze the performance of the hardware and software have traditionally been sparse and vendor-specific.
Performance pathologies can be found in almost any software, from user to kernel, applications, drivers, etc. At Sun we’ve spent the last several years applying state-of-the-art tools to a Unix kernel, system libraries, and user applications, and have found that many apparently disparate performance problems in fact have the same underlying causes. Since software patterns are considered abstractions of positive experience, we can talk about the various approaches that led to these performance problems as anti-patterns—something to be avoided rather than emulated.
You work in the product development group of a software company, where the product is often compared with the competition on performance grounds. Performance is an important part of your business; but so is adding new functionality, fixing bugs, and working on new projects. So how do you lead your team to develop high-performance software, as well as doing everything else? And how do you keep that performance high throughout cycles of maintenance and enhancement?
In December 1997, Sun Microsystems had just announced its new flagship machine: a 64-processor symmetric multiprocessor supporting up to 64 gigabytes of memory and thousands of I/O devices. As with any new machine launch, Sun was working feverishly on benchmarks to prove the machine’s performance. While the benchmarks were generally impressive, there was one in particular—an especially complicated benchmark involving several machines—that was exhibiting unexpectedly low performance. The benchmark machine—a fully racked-out behemoth with the maximum configuration of 64 processors—would occasionally become mysteriously distracted: Benchmark activity would practically cease, but the operating system kernel remained furiously busy.