[solved] Qt5.3.1 on Ubuntu 14.04 LTS <> Ubuntu Core 14.04 LTS (both 64bit) performance difference



  • Hi everybody,

    I have got a Qt 5 application that I build in Ubuntu 14.04 64bit and Ubuntu Core 14.04 64bit and I see a difference of about 50% performance between the 2. The one in the full ubuntu uses about 50% and the one in the ubuntu core uses about 100%.

    So I started investigating the difference between the 2 and what I noticed is that when I do LDD in the full and in the core, I get a different output:

    full ubuntu:
    linux-vdso.so.1
    libcgos.so
    libudev.so.1
    liblttng-ust.so.0
    libdl.so.2
    libftdi.so.1
    libQt5Quick.so.5
    libQt5Multimedia.so.5
    libQt5Qml.so.5
    libQt5DBus.so.5
    libQt5SerialPort.so.5
    libQt5Concurrent.so.5
    libQt5Sql.so.5
    libQt5Gui.so.5
    libQt5Core.so.5
    libpthread.so.0
    libstdc++.so.6
    libm.so.6
    libgcc_s.so.1
    libc.so.6
    libcgmanager.so.0
    libnih.so.1
    libnih-dbus.so.1
    libdbus-1.so.3
    librt.so.1
    /lib64/ld-linux-x86-64.so.2
    liblttng-ust-tracepoint.so.0
    liburcu-bp.so.2
    liburcu-cds.so.2
    libusb-0.1.so.4
    libQt5Network.so.5
    libGL.so.1
    libpulse.so.0
    libicui18n.so.52
    libicuuc.so.52
    libgthread-2.0.so.0
    libglib-2.0.so.0
    libXext.so.6
    libatiuki.so.1
    libjson-c.so.2
    libpulsecommon-4.0.so
    libicudata.so.52
    libpcre.so.3
    libX11.so.6
    libxcb.so.1
    libwrap.so.0
    libsndfile.so.1
    libasyncns.so.0
    libXau.so.6
    libXdmcp.so.6
    libnsl.so.1
    libFLAC.so.8
    libvorbisenc.so.2
    libvorbis.so.0
    libogg.so.0
    libresolv.so.2

    core:
    linux-vdso.so.1
    libcgos.so
    libudev.so.1
    liblttng-ust.so.0
    libdl.so.2
    libftdi.so.1
    libQt5Quick.so.5
    libQt5Multimedia.so.5
    libQt5Qml.so.5
    libQt5DBus.so.5
    libQt5SerialPort.so.5
    libQt5Concurrent.so.5
    libQt5Sql.so.5
    libQt5Gui.so.5
    libQt5Core.so.5
    libpthread.so.0
    libstdc++.so.6
    libm.so.6
    libgcc_s.so.1
    libc.so.6
    libcgmanager.so.0
    libnih.so.1
    libnih-dbus.so.1
    libdbus-1.so.3
    librt.so.1
    /lib64/ld-linux-x86-64.so.2
    liblttng-ust-tracepoint.so.0
    liburcu-bp.so.2
    liburcu-cds.so.2
    libusb-0.1.so.4
    libQt5Network.so.5
    libGL.so.1
    libpulse.so.0
    libz.so.1
    libicui18n.so.52
    libicuuc.so.52
    libglib-2.0.so.0
    libXext.so.6
    libatiuki.so.1
    libjson-c.so.2
    libpulsecommon-4.0.so
    libicudata.so.52
    libpcre.so.3
    libX11.so.6
    libxcb.so.1
    libwrap.so.0
    libsndfile.so.1
    libasyncns.so.0
    libXau.so.6
    libXdmcp.so.6
    libnsl.so.1
    libFLAC.so.8
    libvorbisenc.so.2
    libvorbis.so.0
    libogg.so.0
    libresolv.so.2

    now the difference between the 2 is that:

    • core uses
    • libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fef6a5e6000)
    • full uses
    • libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f45cd83f000
    • otherwise the same

    So my question is twofold:

    • can this be a performance difference because the one does not use gthread?
    • why different ldd output on same application and binary?

    Thanks in advance,

    Kind regards,

    Tim

    result: it appeared to have been the AMD FGLRX driver


  • Moderators

    Hi,

    Do you mean "CPU usage" rather than "performance"?

    [quote]So my question is twofold: – can this be a performance difference because the one does not use gthread?[/quote]It's hard to say, but it's possible. You need to tell us the hardware specs of both PCs.

    [quote] why different ldd output on same application and binary?[/quote]Because Ubuntu and Ubuntu Core contain different packages.



  • Hi,

    they are the same PC exact same hardware.

    indeed i mean CPU usage.

    after some careful checking i suspecting the AMD fglrx driver for the performance drop.


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