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Replacing Atime With Relatime in the Kernel

Posted by ScuttleMonkey on from the results-apparently-too-much-to-ask-for dept.

eldavojohn writes "Our friend Jeremy at the Kernal Trap has dug up some interesting criticism of atime from Linus Torvalds. As Linus submitted patches to improve relatime he noted: 'I cannot over-emphasize how much of a deal it is in practice. Atime updates are by far the biggest IO performance deficiency that Linux has today. Getting rid of atime updates would give us more everyday Linux performance than all the pagecache speedups of the past 10 years, _combined_.' And later severely beat atime about the head with a pointed stick: 'It's also perhaps the most stupid Unix design idea of all times. Unix is really nice and well done, but think about this a bit: 'For every file that is read from the disk, lets do a ... write to the disk! And, for every file that is already cached and which we read from the cache ... do a write to the disk!'" Well, I guess I can expect my Linux machine to become a little bit faster!"

16 of 416 comments (clear)

  1. Ummm.. by Anonymous Coward · · Score: 2, Funny

    Since I have no idea what atime or relatime actually are, could someone just tell me which kernel settings should be changed re: this story for an ideal desktop system?

    Thanks.

    1. Re:Ummm.. by Anonymous Coward · · Score: 1, Funny

      "Since I have no idea what atime or relatime actually are..."

      For starters
      $ man mount

    2. Re:Ummm.. by nschubach · · Score: 5, Funny

      $ man mount

      How can anyone write that with a straight face?
      --
      Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
    3. Re:Ummm.. by PopeRatzo · · Score: 4, Funny

      I have the noatime line in my fstab.
      Ah, these are the kind of stories I first starting coming to Slashdot for.

      I don't think you can fully realize how poetic a phrase such as the one above can be until you read it with absolutely no understanding, as I do.

      Thank you, ArcherB and thank you, Slashdot.
      --
      You are welcome on my lawn.
    4. Re:Ummm.. by misleb · · Score: 5, Funny

      How can anyone write that with a straight face?


      I'm sure it was written with a gay face.

      --
      "THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
  2. Citation error by Anonymous Coward · · Score: 1, Funny

    Spot the citation/reference error!

  3. Re:Linus did not say that! by Anonymous Coward · · Score: 5, Funny

    My name is Ingo Molnar and you mis-attributed my quote. Prepare to die!

  4. Maybe it's just about the defaults by Anonymous Coward · · Score: 1, Funny

    I don't see a story here, unless he's suggesting that the default be changed, and even then it's a pretty minor story. Damn, if only he had the source code, he could change it.

  5. You fell victim to one of the classic blunders! by stefanlasiewski · · Score: 5, Funny

    "You fell victim to one of the classic blunders! The most famous is never get involved in a flame war on Kerneltrap..."

    --
    "Can of worms? The can is open... the worms are everywhere."
    1. Re:You fell victim to one of the classic blunders! by dcapel · · Score: 5, Funny

      A Slashdot summary wrong? Inconceivable!

      --
      DYWYPI?
  6. Re:Never!! by utopianfiat · · Score: 2, Funny

    I thought I'd tack this onto the FP, but the OP is severely mistaken. First of all, Ingo was the one who finally submitted the patch, and it was also Ingo who made the 'faster than all the improvements over the last 10 years combined' statement.
    If you don't believe me RTFA. I just wish the OP had actually read the article before submitting it.

    --
    +5, Truth
  7. Re:Why not a better "atime" instead of "noatime" by MichaelSmith · · Score: 2, Funny

    Where is Hans Reiser when you need him? This is exactly the type of question he likes to argue about.

    --
    http://michaelsmith.id.au
  8. Re:latest relatime patch by Anonymous Coward · · Score: 5, Funny

    I agree - modifying a text file is a messy complicated business only suitable for the elite super hackers out there. It's much simpler for me to apply the patch and recompile the kernel.

    I kid, I kid.

  9. atime on EXT3, huh? by Trogre · · Score: 4, Funny

    (mount ext3 filesystem with noatime flag)

    $ time for i in `seq 1 10000`; do touch file1.dat; done

    real 0m15.231s
    user 0m3.075s
    sys 0m11.970s

    $ time for i in `seq 1 10000`; do cat file1.dat >>/dev/null; done

    real 0m14.326s
    user 0m2.928s
    sys 0m11.172s

    (remount without noatime flag)

    $ time for i in `seq 1 10000`; do touch file1.dat; done

    real 0m12.629s
    user 0m2.687s
    sys 0m9.772s

    $ time for i in `seq 1 10000`; do cat file1.dat >>/dev/null; done

    real 0m12.401s
    user 0m2.624s
    sys 0m9.624s

    Yes I think I'll stick with atime for now, thanks Linus.

    --
    "Nine times out of ten, starting a fire is not the best way to solve the problem." - my wife
    1. Re:atime on EXT3, huh? by zmotula · · Score: 2, Funny

      >>/dev/null? Unix joke of the year :-)

  10. Re:As a flash fs writer... by Anonymous Coward · · Score: 1, Funny

    Whilst we're at it, we should also get character echo disabled.
    Systems would be so much faster!