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ArsTechnica Explains O(1) Scheduler

Posted by michael on from the time-to-kill dept.

geogeek writes "The recent release of Linux's 2.6 kernel introduces a number sweeping improvements. These can be hard to understand without a background in programming. This week's Linux.ars examines the improved scheduler for an enthusiast audience, concisely explaining its nuances and the practical effects of an O(1) design."

4 of 295 comments (clear)

  1. Ars' Piece by WarpFlyght · · Score: 5, Interesting

    I read this piece yesterday, and while it did "dumb down" the basics (as the first poster noted), I thought it did a very good job of putting it all into a nutshell that those of us not as familiar with Big-O and schedulers in general might easily understand. For Linux.Ars' format, I thought it was of appropriate length, and had enough detail to "belong." I'm sure there are more detailed writeups on the O(1) scheduler in place in 2.6. Does anyone have any links?

    --

    "Aye, and if my grandmother had wheels, she'd be a wagon!" -- Montgomery Scott, ST:III
    1. Re:Ars' Piece by Sloppy · · Score: 5, Interesting
      Windows XP, for example, isn't all that great in this area, and often one process can too easily slow things down. This is even further emphasized when all the processes you're working with are actually the main "explorer.exe" process; eg, you do something in Windows Explorer that blocks (spin up a CD drive) and everything else (the "desktop", task bar, etc) all become unresponsive...

      I actually saw this behavior once on a customer's machine. I closed the CD door, and the machine went unresponsive for several seconds. I was shocked. Then I realized: millions of people think this is normal. And those millions of people live in 2003, not 1983. It was like some sort of Lovecraftian revelation.

      --
      As copyright owner of this comment, I authorize everyone to defeat any technological measure which limits access to it.
  2. Hmm. by Anonymous Coward · · Score: 5, Interesting

    I clicked on this article expecting to see an explanation of how it was that the O(1) scheduler worked, and by what tricks it was able to schedule in O(1) rather than having to spend extra time as extra processes are added, and what the real-life effects of such a situation are.

    Instead the article was just "This is what O(1) is. This is what a scheduler is. This is what "preemptive" means. The 2.6 SMP can load-balance effectively across many processors. I used this really cool mp3 player this week." and just about nothing else.

    Anyone want to explain exactly how it is that an O(1) scheduler is a difficult thing, and how exactly linux 2.6 achieves it?

    -- Super Ugly Ultraman

    1. Re:Hmm. by Crypto+Gnome · · Score: 4, Interesting

      Personally, I *really* like the idea of split-brained articles. (ie such a shame that wasn't done here)

      By that I mean the 'default'/'main' article having the not-too-geeky/JoeSixPack-reads-slashdot version, AND includes a link to "for those who want the gory details".

      That way the editors have an article which appeals to the vast majority of "reasonably intelligent" people, as well as catering to the hardcore techo-savvy crowd. (ie wrote a brainfuck program before breakfast)

      --
      Visit CryptoGnome in his home.