Tech media Phoronix ran a benchmark of the Linux 5.19 kernel built with "-O3 -march=native". The test environment is as follows:
Test results showed that the "-O3 -march=native" kernel build did not yield significantly better performance. The thing is, it even goes backwards in some workloads when building with GCC 11 on Ubuntu 22.04 LTS.
In particular, the "-O3 -march=native" kernel performs not only worse than the -O3 kernel build, but also worse than the -O2 kernel on certain I/O workloads.
From database workloads to basic I/O benchmarks using FIO, it is often seen that "-O3 -march=native" kernels produce results that lag significantly behind less aggressively optimized kernels.
Testers pointed out that the test results were basically a mess. In dozens of benchmarks on this Core i5 12600K desktop, the "-O3 -march=native" optimized cores didn't get any impressive results.
Users who want to drill down to the full test data can view this results page .
Overall, looking at the geometric mean of dozens of benchmarks, the "-O3 -march=native" kernel is actually slightly slower due to regressions in the I/O benchmarks. So, at least on this particular Intel Alder Lake system, the "-O3 -march=native" kernel-optimized build isn't worth it.