November 17, 2010, 5:24 PM — What a difference 233 lines of code can make.
That's the size of a small new patch to the Linux kernel's scheduler that has been found to reduce the average latency of the desktop by about 60 times. It's a small patch with a really, really big gain for desktop users of the open source operating system, in other words.
Though not yet merged into the mainline kernel, the new patch--written by Linux kernel developer Mike Galbraith--has already received high praise from Linux creator Linus Torvalds himself.
"I have to say that I'm (very happily) surprised by just how small that patch really ends up being, and how it's not intrusive or ugly either," Torvalds wrote Monday in an e-mail. "I'm also very happy with just what it does to interactive performance.... It is a _huge_ improvement."
Web pages, in particular, load "a lot faster" following the patch, Torvalds noted. "I think this is firmly one of those 'real improvement' patches. Good job. Group scheduling goes from 'useful for some specific server loads' to 'that's a killer feature'."
60 Times Faster
Essentially, the patch works by automatically creating task groups per TTY--or input/output device--so as to improve desktop interactivity under heavy loads. The feature is enabled from boot by default, but it can be turned on or off on the fly.
In tests by Galbraith, the patch reportedly produced a drop in the maximum latency of more than 10 times and in the average latency of the desktop by about 60 times. Though the merge window is now closed for the Linux 2.6.37 kernel, the new patch should make it into version 2.6.38.
Two contrasting videos on Phoronix demonstrate the difference the patch makes.
The New Speed Demon
Linux has just recently made a round of fresh headlines for its stellar performance on supercomputers--the current leader in that race runs the open source operating system, for example, as do the majority of the top 500.