I want to know if the O(1) scheduler code, which was used in earlier versions of the Linux kernel, still exists in the current kernel source code. If it has been completely removed, which version of the Linux kernel was the last to include it? Any guidance or references to relevant parts of the source code would be greatly appreciated.
I found out that it is replaced by the CFS but don’t know if the source code still exists.
The O(1) scheduler was replaced by the CFS scheduler in the 2.6.23 kernel and it was pretty major rewrite of sched.c. The CFS scheduler was in turn replaced by the EEVDF scheduler in the 6.6 kernel.
Small bits and pieces may exist in current kernels but the major algorithms were rewritten and the sched.c file doesn't even exist any more as the functionality has been split across other files.