Friday, April 27, 2007

New Linux Kernel: 2.6.21

It took longer than Linux creator Linus Torvalds would have liked, but the latest Linux kernel, version 2.6.21, has arrived. It brings many minor and major changes in how Linux handles process scheduling and time. In his April 25th release note to the LKML (Linux Kernel Mailing List), Torvalds wrote, "If the goal for 2.6.20 was to be a stable release (and it was), the goal for 2.6.21 is to have just survived the big timer-related changes and some of the other surprises." Surviving all those changes took time. "It's been over two and a half months, and while it's certainly not the longest release cycle ever, it still dragged out a bit longer than I'd have hoped for and it should have."

The delays came in large part because of "all the timer changes to support a tickless system (and even with ticks, more varied time sources)." Torvalds called timer-related improvements "the big change during 2.6.21." A tickless system you ask? In 2.6.21, new technologies called clockevents and dyntick (dynamic ticks) were introduced. The technologies are based on previous real-time Linux work by Ingo Molnar and Thomas Gleixner. Together, they make the new kernel more efficient, both in terms of saving power, and in terms of dealing with heavy-duty multi-tasking jobs such as virtualization.

Linux-Watch.com

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