Profiling
Core Technology
We all want our programs to run fast. With profiling, you can locate the code that is slowing you down and fix it.
While hardware becomes faster and faster, the software it runs becomes slower and slower. Although this is a joke, it carries a bit of truth. Quite often, the software uses suboptimal algorithms, introduces costly abstractions, or misses hardware caches. This is okay most of the time, because hardware is forgiving and has enough capacity for many tasks. The rest of the time, you want your code to perform as fast as possible.
Optimizing a program is not the same as rewriting it from scratch the right way. The majority of code is generally not in the "hot path." It's executed only once in awhile during the program's lifetime, and investing optimization efforts into these parts will never pay off. So, you need a tool to tell you which code paths are consuming most of the CPU time.
A technique called "profiling" comes into play here. You build an execution profile of the program (hence the name) that tells you which functions the program runs and how much time they take; then, you look at the profile and decide what you can do about it. While the last step is a bit of an art, the first step just requires a tool that is essential to any developer. Luckily, Linux offers several such tools.
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