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Hi, [Apologies to readers of forums.debian.net, but I tried asking this there and got no response.] I have eight identical server platforms, but with two different Linux operating systems on ...
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  1. #1
    Just Joined!
    Join Date
    Dec 2009
    Posts
    12

    Debian Wheezy running extremely slowly


    Hi,

    [Apologies to readers of forums.debian.net, but I tried asking this there and got no response.]

    I have eight identical server platforms, but with two different Linux operating systems on them, and the performance I get is hugely different depending on the Linux distro. Obviously, I need to know why. Specifically, one is Debian Wheezy 7.1 and the other is Ubuntu 12.04.3, and the Debian ones run at about 50% the speed of the Ubuntu ones. So, here are the hardware specifications per node:

    Intel H2312JFKR server board
    2 x Intel Xeon E5-2650 (8 cores each)
    128 GB ECC 1600 MHz RAM (verified via dmidecode)

    The OS information is (from uname -a):

    For a Debian machine: Linux <hostname> 3.2.0-4-amd64 #1 SMP Debian 3.2.46-1+deb7u1 x86_64 GNU/Linux
    For an Ubuntu machine: Linux <hostname> 3.2.0-51-generic #77-Ubuntu SMP Wed Jul 24 20:18:19 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

    In order to benchmark their performance, I've run a couple of Phoronix (version 4.8.3) tests, namely:

    Memory test: pts/ramspeed-1.4.0
    Processor test: pts/byte-1.2.0

    The full results can be seen online (see references below), but the upshot is that a Debian machine runs at only about 60% of an Ubuntu platform in the memory tests, and only 50% for the processor speed tests. I've even set the processor governor to "performance" on the Debian machines by doing:

    1) In /etc/default/cpufrequtils, set:
    GOVERNOR="performance"

    2) In /etc/modprobe.d/ignore_ppc.conf, set:
    options processor ignore_ppc=1

    Hence, for all Debian cores I have:

    % cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq
    2001000
    <and 31 other identical entries>

    So that should be the maximum speed, but I also strangely always have:

    % cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
    1200000
    <and 31 other identical entries>

    By contrast, I do see the Ubuntu machines cpuinfo_cur_freq values vary up to 2001000. Is there any reason why this should be, and is this a symptom or a cause of the problem?

    Thanks for any help!

    ===

    Online Phoronix results (prepend URLs with http ://)

    Ubuntu:

    Memory - openbenchmarking.org/result/1310073-SO-MEMTEST8333
    Processor - openbenchmarking.org/result/1310078-SO-PROCTEST859

    Debian:

    Memory - openbenchmarking.org/result/1310072-SO-MEMTEST3693
    Processor - openbenchmarking.org/result/1310070-SO-PROCTEST759

  2. #2
    Linux Newbie
    Join Date
    Sep 2007
    Posts
    218
    You might check /boot/config-xxxx for a difference in frequency timing... Debian's stock kernel is CONFIG_HZ=250.

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