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    Qt World Summit: Early-Bird Tickets

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

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    • T
      t.verstraete last edited by

      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

      1 Reply Last reply Reply Quote 0
      • JKSH
        JKSH Moderators last edited by

        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.

        Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

        1 Reply Last reply Reply Quote 0
        • T
          t.verstraete last edited by

          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.

          1 Reply Last reply Reply Quote 0
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