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Bisected: The Unfortunate Reason Linux 4.20 Is Running Slower

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  • Bisected: The Unfortunate Reason Linux 4.20 Is Running Slower

    Phoronix: Bisected: The Unfortunate Reason Linux 4.20 Is Running Slower

    After running a lot of tests and then bisecting the Linux 4.20 kernel merge window, the reason for the significant slowdowns in the Linux 4.20 kernel for many real-world workloads is now known...

    http://www.phoronix.com/vr.php?view=27092

  • #2
    Good it wasn't a kernel regression but a mitigation that can be disabled for performance.

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    • #3
      how many more speedhacks there are in intel cpus that sacrifice security? it just never ends.

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      • #4
        Hardware is cheap these days. Buy new and faster hardware. More RAM and a faster SSD.

        ... just wanted to use the same arguments that people throw at my head, when it comes to horrible GNOME performance.

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        • #5
          With all security mitigations enabled Skylake has lower IPC than Bulldozer... And they called Bulldozer a "failure". Sure, when you don't care about security at all you can get better IPC... How come AMD didn't think of this?

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          • #6
            Originally posted by Candy View Post
            Hardware is cheap these days. Buy new and faster hardware.
            Like upcoming Zen 2?

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            • #7
              Originally posted by Candy View Post
              Hardware is cheap these days. Buy new and faster hardware. More RAM and a faster SSD.

              ... just wanted to use the same arguments that people throw at my head, when it comes to horrible GNOME performance.
              Is there a Godwin point variant for DE holy wars?

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              • #8
                Wow! That was quick, great work Michael thanks. Yesterday I finally remembered to turn off ad-blocker and have been doing my part to make sure you get paid for the time I spend frequenting here.

                I'm so glad I turned all that shit off in GRUB, and stopped Intel from feeding me new microcodes on my Haswell.

                Code:
                $ dmesg | grep 'microcode'
                [    0.000000] microcode: microcode updated early to revision 0x22, date = 2017-01-27
                [    0.495848] microcode: sig=0x306c3, pf=0x2, revision=0x22
                [    0.495866] microcode: Microcode Update Driver: v2.2.
                
                $ sudo apt-mark showhold
                intel-microcode
                iucode-tool
                
                $ grep 'GRUB_CMDLINE_LINUX_DEFAULT' /etc/default/grub
                GRUB_CMDLINE_LINUX_DEFAULT="quiet pti=off spectre_v2=off l1tf=off nospec_store_bypass_disable no_stf_barrier"
                Friends don't let friends use Spectre mitigations on their desktop/notebooks.

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                • #9
                  I wonder if Hyperthreading is still worth it? Would it be interesting to run a speed test with it disabled?

                  Comment


                  • #10
                    Originally posted by Zan Lynx View Post
                    I wonder if Hyperthreading is still worth it? Would it be interesting to run a speed test with it disabled?
                    Intel may have already answered that question internally. Remember the recent chip marketing that only mentioned number of cores, no mention of threads or HT....

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