Michael Dolan Dot Com

Thursday, April 26th, 2007

Linux 2.6.21 kernel arrives

As SVN reports, Linus has signed off on 2.6.21 with new innovative features to help with real-time, virtualization, and power usage (yes, a greener Linux). Two big features arrive with 2.6.21.

First, there’s clockevents:

The clockevents feature provides a uniform interface and a device API for a computer’s various timekeeping and scheduling devices. With this, developers don’t need to delve down to the hardware level to work with a computer’s timing mechanisms, making it much easier to program extremely accurate timekeeping.

Then there’s dynticks (looks like we’re getting closer to a mainframe virtualization eh?):

dynticks, saves power by shutting down the system clock more completely during periods of idleness. With earlier kernels, the system clock keeps “ticking” the timer interrupt even when the system has gone idle, at a rate of 1,000 ticks per second, or 1Hz. That wastes a lot of Watts when the CPU is doing nothing but virtually twiddling its thumbs waiting for another job. With Dynticks, the timer interrupt is turned almost off and the CPU waits for a real interrupt to come from a program, network interface, or the like. By idling your processor, you save energy — and on a laptop, that’s not a small matter.

Dynticks is one feature I’m thinking of compiling a new kernel to get… while writing this, I see that Gentoo sources already has an x86 kernel source for 2.6.21 ready to go :-)