Chapter 21
Executing Too Much
This chapter is a short case study of a transaction-server program whose intermittent performance problem is too much CPU-bound user-mode execution.
21.1 Overview
We will discover that the slow transactions execute too much code, i.e., that the slow instances involve a different longer and/or slower code path than the fast instances. In all these case studies, what we “know” about a program’s behavior is the picture in our head. That differs, sometimes substantially, from reality. Treat the word know as a yellow flag that unsupported assumptions follow. In contrast, the word measurement refers to real-world behavior as observed by low-distortion tools. Treat these measurements as more reliable than the picture ...
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