[cliffbean]

I find perf a very useful tool, and use it frequently.

At the same time, I don't see how your data supports your conclusion that perf is more effective than cachegrind here. The absolute cycle count is of limited interest. The most important thing these tools do is tell programmers where to look, and cachegrind seems to have done a good job of that here.

In my experience, perf and cachegrind are two tools in the toolbox. perf is stronger at optimizing for the particular CPU I'm on, and it runs faster. Cachegrind collects more detailed information, and while the model it uses isn't perfect for the CPU I'm on today, it's usually good enough to be useful, and it's good for optimizing things likely to matter on other CPUs too.