Beautiful branchless binary search

How does the benchmarking work here? I always find this kind of micro-benchmarking hard. I feel like I want to see results with and without a preceding cache flush. And with/without clearing of the branch predictor state. Other things I find hard are: 1) ensuring that the CPU is running at full(ish) speed and isn't in a slower-clocked power saving mode for some of the test, 2) effects of code and data alignment can be significant - I want to measure a bunch of different alignments.

Does gtest (that the author used) help with these things? Does anything?

Running within a linux cset shield is a fairly standard practice.

For benchmarks reporting times in the range of nanoseconds a common approach is a linear regression of varying batch sizes; I'm not sure gtest does this.

But generally, don't trust any result without a (non-parametric) confidence interval, since the confounding factors like OS jitter, CPU frequency, temperature etc. can't be easily controlled, although some CPU features can be disabled.

According to Intel, for accurate benchmarking you should write a Linux kernel module. And remember to disable preemption and disable interrupts.

https://www.intel.com/content/dam/www/public/us/en/documents...