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

t.verstraete

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

JKSH

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.

t.verstraete

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.