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The Huge Disaster Within The Linux 2.6.35 Kernel

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  • The Huge Disaster Within The Linux 2.6.35 Kernel

    Phoronix: The Huge Disaster Within The Linux 2.6.35 Kernel

    For the past six months we have been monitoring the performance of the very latest Linux kernel code on a daily basis across multiple systems. We have spotted a few regressions -- both positive and negative -- on occasion using our automated daily testing of the Linux kernel, but nothing like what we have encountered the past few days: the Linux 2.6.35 kernel performance has fallen hard. In fact, the performance has fallen very hard in a number of tests and right now, we would consider it a disaster. While the 2.6.35 code has not even seen its first release candidate yet, there are some massive performance drops in a variety of different tests that have yet to be corrected and nothing like we have encountered with previous kernel release cycles especially for a regression that has lived now for about one week.

    http://www.phoronix.com/vr.php?view=14976

  • #2
    very curious what caused it- anybody know specifically?

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    • #3
      Did I ever post my code for determining whether it was CPU or I/O bound? I'm in the middle of another project at the moment, but meanwhile, here's the algorithm:

      http://borasky-research.net/2010/02/...neck-analysis/

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      • #4
        you know, i thought that the purpose of kernel regression tracker was not to make 5 pages of graphs and drama but pinpoint the offending commits.

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        • #5
          It's almost certainly not io bound, given some of those benchmarks. That's what makes it a lot more interesting than some of the previous "regressions" Phoronix has reported on that were just safer defaults on the file system.

          If this was my own software, I'd be looking for a new lock somewhere that's coming under a lot of contention and starving the other running threads, but I suppose with a kernel it could be just about anything.

          I agree that this article would have been a lot better if Michael just ran the git bisect and at least narrowed it down a little. It sounds like he's had plenty of time to look into it. That line near the end of the article almost sounds like he's fishing for money from someone to pay him to do it.

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          • #6
            Originally posted by smitty3268 View Post
            I agree that this article would have been a lot better if Michael just ran the git bisect and at least narrowed it down a little. It sounds like he's had plenty of time to look into it.
            I suspect he wants to stretch this out into 4 or 5 articles. He can't do that if he figures it all out ahead of time.

            Seriously, is the edit timeout thing never ever going to be fixed?

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            • #7
              We waited nearly a week to see if these regressions would be organically caught and addressed, but they have not been at least of the Linux 2.6 Git state as of 2010-05-26.
              What nonsense ...
              Seriously when you find bugs report them and not just wait and assume that they get magically fixed.

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              • #8
                OMG what drama

                this is a .35-rc1 kernel for crying out loud!

                beside that, the quality of articles here on phoronix has been nose diving for a while now. I'm even beginning to get annoyed.

                Michael, you have to do better and you can because it was good in the beginning. Articles like this are total crap and do you and your site no service at all

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                • #9
                  Originally posted by drago01 View Post
                  What nonsense ...
                  Seriously when you find bugs report them and not just wait and assume that they get magically fixed.
                  Exactly. I'm getting sick of these articles boasting "we've found a problem, but we've kept it a secret".

                  Michael, have you contacted Linus? Have you reported it as a bug? Phoronix would get a lot more credit if the articles were more like: "We found a regression and it's already fixed in Linus' tree thanks to Phoronix".

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                  • #10
                    http://lkml.org/lkml/2010/5/22/150

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