The Linux kernel process scheduler, as you know it, has been completely ripped out and replaced with a completely new one called Completely Fair Scheduler (CFS).

In a continued thread about how the recently merged Completely Fair Scheduler affects the nice command, Ingo Molnar offered a history of nice levels in the Linux kernel.

If you’ve been following Linux kernel news then you’ve probably heard about the new Completely Fair Scheduler that has been merged into the upcoming 2.6.23 kernel release. I decided to do a bit of research into how the current Linux scheduler works, and what makes the new scheduling algorithm so interesting. Here’s what I learned.

Con Kolivas, who worked on desktop interactivity issues in the past before storming off in 2007, has posted a new scheduler called BFS.

"As some of the latency junkies on lkml already know, commit 8e3e076 in v2.6.26-rc2 removed the preemptible BKL feature and made the Big Kernel Lock a spinlock and thus turned it into non-preemptible code again. This commit returned the BKL code to the 2.6.7 state of affairs in essence," began Ingo Molnar.

A number of senior kernel developers, including Linus Torvalds, Ted Ts'o, Alan Cox and Ingo Molnar, have been squabbling over the sense or otherwise of journaling and delayed allocation in Ext3 and Ext4.

Today kernel developer Con Kolivas announced that he will stop developing his Linux patch which improves desktop performance. For people who have followed recent discussions about his SD CPU scheduler and about the inclusion of his swap prefetching patches in the Linux kernel this will not come as a surprise.

The Linux scheduler is an interesting study in competing pressures....Although Linux was originally developed as a desktop operating system experiment, you'll now find it on servers, tiny embedded devices, mainframes, and supercomputers. Not surprisingly, the scheduling loads for these domains differ.

A few weeks back Con Kolivas returned to the Linux kernel scene after parting ways with kernel development for two years. Con, who has contributed a great deal to the Linux kernel in the past particularly with CPU schedulers, returned and introduced BFS.