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Showing posts from January, 2011

More on Performance Rules: Context is King

As discussed in the last blog entry, unfortunately, an automated, rules-based, expert systems approach to diagnosing performance-related problems turns out to be too brittle to be very effective. The simple threshold-based rules invoked by various authorities often need to be fleshed out with additional conditions and exceptions. Once the rule is burdened with all the predicates necessary to qualify an expert’s assessment of the data in context, the automated reasoning process starts to break down. It turns out it isn’t so easy to encapsulate an expert’s knowledge and judgment into a simple, declarative rule. The expertise a performance analyst cultivates can involve pattern matching based on experience with many other incidents with similar problems encountered in the past. Where the human diagnostic expert often indulges in intuition based on that background and professional experience, it is difficult to craft a mathematical or logical rule that can accurately mimic that reasoning …

Performance Rules!

Around the time that Odysseus Pentakalos and I were writing our original book (the Windows 2000 Performance Guide from O’Reilly), there were already several books in print that provided guidance on Windows NT performance topics. (Internally, Windows 2000 is Windows NT version 5.0, while the current Windows 7 OS is version 6.1). In my travels, I had read several of these, along with almost every technical article on the subject I could get my hands on. While these Windows performance books all had some merit, I also found they had serious shortcomings, in my less than humble opinion. Unfortunately, none of them were written with the benefit of understanding the Windows operating system from the inside out, which was largely a black box until the publication of David Solomon’s original “Inside Windows NT” in 1998. (You can check out the review of the Solomon book I wrote for Amazon almost immediately after it was published here.) Moreover, none of those early books relied on a systemati…

Not quite ready for Twitter

It might be helpful to set a few expectations up front to Readers of this blog about what kind of blogging you can expect from me, with the added caveat that I believe such expectations are made to be broken... As an adjunct to my day job as a software developer, Ihavewritten & published numerous articles on topics related to computer performance over the years. Since about 1996, I have been focused on Windows, so I was mainly writing and publishing articles on Windows performance and scalability topics. (If you are interested, many of these early articles are available on the DemandTech web site here: http://demandtech.com/knowledge_perspectives.html. More concise answers written in response to FAQs are published here: http://faq.demandtech.com/.) In the past, I often published similar material in industry newsletters, trade magazines, and in the official publications of the Computer Measurement Group, a professional association that I joined in 1983 and remained active in for yea…

Performance By Design: Welcome

Welcome to a blog devoted to Windows performance, application responsiveness and scalability, software performance engineering (SPE), and related topics in computer performance. My name is Mark B. Friedman. I am a professional software developer, author of several popular software products over the years, many of them tools used in computer performance analysis and capacity planning. I have chosen “Performance By Design” as a title for this blog. This is partially an homage to one of the best books I know on software performance engineering, “Performance By Design,” written by Daniel MenascĂ© and his colleagues. If you follow the link provided, you will see that I have given the book a well-deserved five-star review on Amazon. I admire Dr. MenascĂ©’s book. I aspire to be able to write as succinctly and thoughtfully on the same topics. I also thoroughly like the title. The clear implication of the phrase “performance by design” is that acceptable levels of application performance don’t ju…