How Google uses Linux OS

I came across this interesting article that talks about how is Linux being used at Google. There is not much specific information how the tasks are scheduled and all. This was a talk between Google Folks and the Kernel Developers. Google has ported some old code to run on the kernel version that they use. It also tells us that Google uses an old kernel like 2.6 etc Well you can read the whole article at lwn. Its interesting read.