Is there something special about Linux kernel 2.6? if yes, then would like to know what are they.
Any insights on kernel 2.6 would be helpful.
not sure if it can be in your interest, btw,
2.6.23 (October 2007) was the version where the CFS was introduced. You may be interested on reading the story of the scheduler, there are some curious aspects.
This is the default scheduler used still now a day, even if extended with some features. It's cool, at least me, looking on the scheduler code, cannot understand anything about. And i believe few in the world (a part of course the author) really know how it works.
As far as i see, in kernel 2.6 there was a lot of other improvements, one i remember is, from version around 2.6.30, IRQ threads was introduced, enabling the developers to write the "top half" part as a simple IRQ function that wakes up the specialized interrupt thread. In this way, the "bottom half" part is run later on in the threaded part. With some variants, the same concept is used now a day (threaded irq stuff).
So kernel 2.6 for many aspects was a kind of really "epic" release, even if there is good job in each other.