Intel's Clear Linux Taps -O3 For Its Kernel Builds
The upstream kernel has dropped the dedicated -O3 option but higher optimization levels can still be passed to the kernel via the compiler flags, which is what Clear Linux is doing.
Following a ticket about having the kernel built with the higher -O3 optimization level, Clear Linux's kernel package has switched to -O3 for hopefully juicing a bit more out of the kernel.
Granted, from my own recent -O3 kernel build benchmarks, most kernel-sensitive workloads tended to have just minor gains if at all. In any case it will be interesting to see how well the -O3'ed kernel works for Clear Linux on top of all their other speed optimizations for maximizing Linux x86_64 performance. Meanwhile their kernel "-march=" target continues to be Westmere as at the bottom end of their Intel hardware support spectrum.