Updating the pluggable scheduler patches for the 2.6.22 kernel, Peter Williams noted, "probably the last one now that CFS is in the main line". CFS author Ingo Molnar asked, "why is CFS in mainline a problem? The CFS merge should make the life of development/test patches like plugsched conceptually easier." Peter explained, "it means a major rewrite of the plugsched interface and I'm not sure that it's worth it (if CFS works well). However, note that I did say probably not definitely :-). I'll play with it and see what happens."

Ingo went on to suggest, "most of the schedulers in plugsched should be readily adaptable to the modular scheduling-policy scheme of the upstream scheduler. I'm sure there will be some minor issues as isolation of the modules is not enforced right now - and i'd be happy to review (and potentially apply) common-sense patches that improve the framework." Peter wasn't entirely convinced, but added, "I don't feel like converting staircase and nicksched as I have no real interest in them. Perhaps I'll just create the interface and some schedulers based on my own ideas and let others such as Con and Nick add schedulers if they're still that way inclined." In response to Ingo's offer to review the work he noted, "thanks for the offer of support (it may sway my decision)".

Ingo Molnar [interview]'s Completely Fair Scheduler [story] has been merged into the Linux kernel for inclusion in the upcoming 2.6.23 release. A comment in the patch titled 'sched: cfs core code' noted, "apply the CFS core code. This change switches over the scheduler core to CFS's modular design and makes use of kernel/sched_fair/rt/idletask.c to implement Linux's scheduling policies." Another patch included documentation which described the new scheduler, "80% of CFS's design can be summed up in a single sentence: CFS basically models an 'ideal, precise multi-tasking CPU' on real hardware." It goes on to explain:

"CFS's task picking logic is based on this p->wait_runtime value and it is thus very simple: it always tries to run the task with the largest p->wait_runtime value. In other words, CFS tries to run the task with the 'gravest need' for more CPU time. So CFS always tries to split up CPU time between runnable tasks as close to 'ideal multitasking hardware' as possible.

"Most of the rest of CFS's design just falls out of this really simple concept, with a few add-on embellishments like nice levels, multiprocessing and various algorithm variants to recognize sleepers."