Category Archives: Computer Tips

how to fix wpf take up too much cpu on vmware

For some unknown reason, wpf may take up way to much cpu % on vmware, a workaround is to turn off hardware acceleration, add this dword value in the registry editor:
path: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Avalon.Graphics\DisableHWAcceleration
value: 1
create the folder if not already exist.


Setup qemu and bridged network on ubuntu

Install qemu
apt-get install qemu-kvm virt-manager virt-viewer libvirt-bin bridge-utils
If it doesn’t work, use this:
apt-get install qemu-kvm qemu virt-manager virt-viewer libvirt-bin bridge-utils

Unfortunately, you don’t get the bridged network by default, so this is what has to be done:
stop network-manager
echo "manual" | tee /etc/init/network-manager.override

And you need to change your interface file like this:
auto br0
iface br0 inet static
bridge_ports eth0
bridge_stp on
bridge_maxwait 0
bridge_fd 0

Also add the ‘/etc/sysctl.conf’ settings to the end of the file:
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0

Apply the changes:
sysctl -p /etc/sysctl.conf

To my surprise even this is needed:
Add to /etc/rc.local:
/sbin/sysctl -p /etc/sysctl.conf
iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
exit 0

Root or run something like this:
ifdown eth0 && ifup br0

And last but not least, with br0, beloved eth0 seems gone forever, I don’t like this, but what other choice I have.

ubuntu boot into textmode

pico /etc/default/grub
And Do below changes:

Comment the line GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash”, by adding # at the beginning, which will disable the Ubuntu purple screen.
Change GRUB_CMDLINE_LINUX=”” to GRUB_CMDLINE_LINUX=”text”, this makes Ubuntu boot directly into Text Mode.
Uncomment this line #GRUB_TERMINAL=console, by removing the # at the beginning, this makes Grub Menu into real black & white Text Mode (without background image)

And run this after:


Join mp4 files with mp4box

First of all need a linux system, if you have a windows try to find a windows version of mp4box
On ubuntu, install the package that contains mp4box:
aptitude install gpac
then run the command like this to join or merge the mp4 files
MP4Box -cat path/to/video1.mp4 -cat path/to/video2.mp4 -cat path/to/video3.mp4 -new path/to/output.mp4